View Full Version : Kestrel Mayday (TCAS discussion)

11th Mar 2003, 13:25
Heading north over Barcelona this morning (11th March) at abot 0940 I hear the following conversation:

Kestrel 203: "Mayday Mayday Mayday, Kestrel 203 engine failure, descending to FL 100"

Manuel (for it is he): "Say again?"

Kestrel 203: "Mayday Mayday Mayday, Kestrel 203, engine failure, descending to FL 220 (wise move that!) turning on to heading 145"

Manuel: "Roger"

I 'followed' Kestrl 203 through all the frequencies (on box 2) until he went to BCN tower on 118.1 when he was blotted out by (I think) Toulouse tower. Hope all went well despite [apparent] lack of assistance or even interest by the Spanish controllers.

Boeing or Airbus?

11th Mar 2003, 14:28
sources say it was a A320

11th Mar 2003, 15:38
All is well, aircraft landed safely

Tcas climb
11th Mar 2003, 16:50
Boeing or Airbus?

Does that matter? What is more interresting is who made the engine.

11th Mar 2003, 17:09
Oh! come on, TCAS - how on earth are we going to get ANOTHER Boeing v Airbus thread going with an attitude like that? :rolleyes:

Vortex what...ouch!
11th Mar 2003, 17:18

Glad to see it ended without misshap. Well done to the people at the front :cool: Poshbird any other info?

11th Mar 2003, 17:51
Boeing or Airbus?

Does that matter? What is more interresting is who made the engine.

Not wishing to start an Airbus vs Boeing thread, but it seems hard to imagine a Mayday call that doesn't involve an issue with the airframe.

11th Mar 2003, 17:56
Oh dear! I hope I haven't opened up another Boeing v Airbus argument! It was just that I used to work for the company concerned and was curious, that's all!

11th Mar 2003, 22:31
> Hope all went well despite [apparent] lack of assistance or even interest by the Spanish controllers.

I was the first person to hear that and I must admit it makes me sad to hear what you say.
As you can imagine, when there are so many lifes at stake, the last thing one wants to do (both proffessionally and personally speaking) is to ignore such an emergency.
Nonetheless, just in case anyone is not aware, strict set emergency procedures have to be followed in these cases, both in the cockpit and in the control room.

There was everything except lack of interest and I should tell you that as a controller the last thing you can do is to disturb the pilot when he is facing an emergency like this.

These comments do not do anything good but alarm and missinform people and just to put your mind at rest, YES, everything went allright because everybody did what they had to do at all times despite what you call a lack of interest.

11th Mar 2003, 22:39
Why should it not be a Mayday call?? The aircraft lost 50% of its power and I was taught that situation = Mayday. On top of which the aircraft was UNABLE TO MAINTAIN HEIGHT and wasn't requesting descent, but telling ATC they were descending regardless, and that is 100% a Mayday.

As for my Spanish comrades, probably more a lack of experience with handling emergencies than anything else. UK ATC was one of the first to get a full and compulsary emergency training course going and now its a yearly session, however I know many others do it much different.

11th Mar 2003, 23:22
Technically, a MAYDAY is declared when the aircraft is threatened by "grave and imminent danger" and requires "immediate assistance".

PAN is appropriate to an aircraft being in a state of "urgency".

However, in the real world I would not blame any aircraft commander who declares a MAYDAY should this be deemed necessary.

I see to recall a thread a long while ago which implied that Spain and several other states did not recognise the PAN status.

12th Mar 2003, 00:30
A few points here from a Controllers point of view.
Firstly.as has been previously state a 50% percent loss of power controllers are taught should lead to a "Mayday" call (just typing the word makes my blood freeze!).
Secondly, as has been previously stated, a controllers first response to a "mayday" calll will be simply "Roger Mayday". this is not disinterest on the part of the controller but what is taught because it is understood that the cockpit workload has just gone through the roof.
Finally, what appear to be periods of silence on the R/T,are actually the controller phoning everyone around to clue them into the situation and the possible repurcussions.
Sometimes what pilots fail to realise about the job of ATC is that only about 30% of the job is talking on the R/T, the rest is co-ordination between different units and agencies. This percentage increases dramatically on the co-ordination side in the event of an emergency situation.
A classic situation for this is a (fingers crossed) incident at an airfield, where the controller may be too busy to talk to you because he is phoning the fire service, ambulances ,police, d+d and airfield operations. it is not to say that the incident has been trivialised, indeed it is to say that it is being treated with the upmost urgency.

12th Mar 2003, 00:55
Very good repplies from the ATC guys....:ok:

12th Mar 2003, 06:35
Interesting comments about PAN v Mayday...

A few weeks back I would have agreed with the thoughts about a Mayday being OTT for an Engine Failure in the cruise.

Whilst covering "Discussion Points", during a course with a TC, the issue arose, and I now agree a Mayday is more appropriate. As has been stated above "requires immediate assistance" is 100% the case. We ARE coming down NOW - no choice - we NEED IMMEDIATE ATC assistance to clear the decks below.

In fact, the need for assistance is more compelling here than an Engine Failure at rotation. The moment ATC have cleared you to descend to a FL at or below SE MAx Alt, the urgency is over, and a downgrade to PAN appropriate.

Personally, most of my (sim) PAN / Mayday calls tend to follow with the word "Standby". I am glad to see Spanish ATC did not follow up with 20 questions...

And as for <<Boeing or Airbus? >> shouldn't it be <<CFM or IAE>> !!


12th Mar 2003, 08:43
I have been thinking about this, and have to agree that with todays crowded skies, descending without clearance could put you in "grave and imminent danger".
-You don't really have any way of assessing that danger in advance (you don't have the traffic picture below you).
-You can't respond to the TCAS god when he commands "climb, climb now". That will definately upset the other guy descending, descending now.

Maybe some companies need to update their SOPs?

Johnny F@rt Pants
12th Mar 2003, 08:45
Having passed through BCN last night I assme it was the A320 that is now sitting on a relatively remote stand.

Very well done to all concerned.

WRT Mayday or not, an engine failure at any stage is definitely a very serious occurence and requires immediate assistance, therefore it is most definitely a Mayday call, you want anything and everything shifted out of your way immediately, and a dedicated freq if you can get it.

Terrain Ahead!
12th Mar 2003, 10:02
Our SOP (not MYT) is engine failure ---> MAYDAY.


12th Mar 2003, 10:12
Update SOPs??
If you cant maintain altitude, then you cant maintain...! What do you want the guy to do? Update the SOPs to read: Dont descend even though the aircraft is unable to maintain!!
We had a CRJ2 lose an engine and he immediatly lost 3000ft until he managed to hold FL254. He didnt bother descending any further to make it a round flight level, because I guess every foot of altitude proves its worth if the other engine should decide to give up too....

12th Mar 2003, 10:18
Just to clarify that ATC considers it Mayday when 50%+ power has been lost. Its not that we aren't overly concerned by a 747 using only 3, there is always that 'if one's gone, so could the rest' so priority will still be given, but its not exactly going to affect a safe landing somewhere suitable, so a Pan is more appropriate.

On a point of ATC interfering at the wrong time, what would you prefer, a couple of questions every few mins, all the questions at once for you to answer when able, or for us to just say we have questions, and wait for you to come back?? Bear in mind, for some pieces of info we need to know immediately, ie FL needed, and diversion adme if its close so they can get all services present. For instances of engine failure, knowing if it was a routine shutdown, or due fire, and if fire still burning etc is needed, and this also prompts which way do you wanna turn (hear that fire determines this now) all the things we need to know to be able to give you the safest a/c free path possible. As has been said so many phone calls take place to organise this our time is crutial too, not forgetting the recall of staff to man a discrete frequency. We may have many bodies around to help, doesn't mean its any easier :)

12th Mar 2003, 10:20
Reading the thread title, I wondered if it referred to one of their aircraft or the company itself.

12th Mar 2003, 10:33
I must admit I am glad to read the last replies.
Considering it was the first real "Mayday" I had to face everything went fine despite all the unseen coordinations and work we had to carry out (the pilots, controllers and everybody else involved) to solve the problem.
I certainly hope not to experience the same situation again but if I do, I hope evertyhing will work as smoothly and proffessionally as it did yesterday.

12th Mar 2003, 10:47
As an ex blip driver at LATCC for a short time, and now on line pilot, I can really appreciate what's going on as we used to do the recurrent emergency training. There's considerable activity off RT because of course the first thing that happens is to give a one to one service for the aircraft in question for a start. There is a better appreciation of the workload / stress going on in the cockpit, and the last thing is to start pressurising the pilot before he has had time to sort things out eg Kegworth.
Mayday it must always be because accidents are often a combination of 4/5 problems which can be interconnected, and although the first instance is loss of 50% power, until stablised at a FL who knows other consequential effects that may turn up. And don't forget that a bogie can wreak havok with other aircrafts planned flights. You can rehearse all you like for incidents but the reality of human behaviour can be very different when faced with crises. I was CRM instructor for a while with Airtours and had the privilege of knowing 2 captains involved in incidents. It's easy in a Sim............
Very well done to controllers and crew

Aviation Trainer too
12th Mar 2003, 10:53
Considering the lack of impact a PanPan has in some countries as they do not recognise at all the time I would always go for the mayday as soon as I am unable to hold altitude, period.

The best line I was ever taught was: if you have two options use the safest! Thus Mayday will always cover any doubt you might have.. (this is a 73 perspective though... 74 or A340 is differant of course)

12th Mar 2003, 10:58
I'll type slowly so that you can keep up. Some co's may need to update their SOPs as it appears that from some comments made by drivers earlier in the thread that they don't consider it a Mayday call to lose an engine and make an emergency descent. I was pointing out that maybe they need to rethink that position, for the reasons given. I sort of realise that they can't maintain height dahhh. But thanks for your input. The adults are talking at the moment. You can have a turn later.

12th Mar 2003, 11:54
I had an engine failure on t/o out of LHR a couple of years ago. All I transmitted was "Mayday (Callsign) engine failure". ATC acknowledged and kept quiet. My colleague and I were left to carry out the drills in peace. To my lasting embarrassment I never said "thanks" to the controller afterwards.

Just because nothing is heard on the R/T, it doesn't mean nothing is happening on the aircraft, nor (I'm sure) on the ground. Quite the reverse in fact.

12th Mar 2003, 12:59
An engine failure may, or may not, be an emergency. It's not wrong to call Mayday, and it's not wrong not to. It depends on the situation. Your call, and you get paid to make that decision.

What of the MyTravel A-330 that landed single engine in ARN a few days ago? Any info on that one? Heard the crew just informed ATC they where coming in on single engine (no Mayday), and ATC made the decision to push the big button.

12th Mar 2003, 16:56
Even in a non-event like you say ManaAdaSystem, some (most) ATC agencies have further procedures themselves as directed by the overall Airport Authority. Captain calls only on one engine, no emergency, ATC have to put on a local standby at the least, possible Full Emergency so the Airport Crews are fully prepared for duty should the a/c on much reduced braking action fail to stop in time. So its not just what the aircrew perceive, we can and often do put on emergency action because we have SOP's of sorts too.

12th Mar 2003, 18:45
<<An engine failure may, or may not, be an emergency. It's not wrong to call Mayday, and it's not wrong not to. It depends on the situation. Your call, and you get paid to make that decision>>


In fact, in the above thread, it is NOT the Engine Failure that warrants the Mayday. It is the immediate, unavoidable descent (if required). As was pointed out, Mayday implies "immediate assistance required", and ATC are unable to assist with the failed engine! They are however, able to immediately assist with the descent, and in slower time (hence maybe downgrade to PAN), with the diversion...


no sig
12th Mar 2003, 19:43
In a very similar event in my company the other week, a PAN PAN was called with no acknowledgement, it took a MAYDAY, re-enforces the point that PAN's don't seem to be picked up on as quickly.

12th Mar 2003, 20:39
I agree with most of the above

in nats air traffic we are encouraged to go for the higher emergency state just in case as it would be easier to downgrade than update the state of emergency and is a way of covering our backs

Hence as was said sort of above you may say no emergency and find a blue flashing light at every runway exit

12th Mar 2003, 21:06

Good stuff;)

very enlightening - it sometimes needs pointing out before you realise whats involved !

13th Mar 2003, 02:39

Assuming you nice ATC chaps can't get the other traffic out of the way. If an aircraft is descending due to an engine failure, it is very unlikely that the TCAS would issue a 'climb' command during coordinated action.

If the aircraft was descending towards another aircraft the level/climbing aircraft would get a 'climb' advisory. If both aircraft were descending the most likely response from the system would be monitor vertical speed!

This should be a moot point though as in any event, aircraft SOPs dictate that the TCAS system is selected to Traffic Advisories only if the aircraft's performance is degraded. This means you would only get traffic information rather than resolution advice to enable you to decide the best way to avoid the threat.

When an engine is lost in the cruise the jet doesn't just plummet to earth, its kinetic energy is used to delay the descent for 30 secs or so whilst you decelerate to min clean. This delay should give the controllers time to clear the area or in procedural airspace the crew time to get onto a 90 away from the threats!

Hope that helps. By the way I thought you were a bit rude to 126.7. Even adults need the facts before they speak; just the other day I asked my 7 year old why she was behaving like a little girl....


El Desperado
13th Mar 2003, 04:27
I'm not sure I agree with some of your points there, Ghost.

The TCAS fitted to our aircraft (757/767) is not fully 'performance aware', i.e the TCAS assumes full a/c performance (at current weight ?) available at all times and is not fed any data on engine failures or shutdowns.

It is therefore perfectly possible for an aircraft on one engine to be issued a Climb RA which cannot be actioned. Thus, as you rightly point out, TCAS boxes should be selected to TA in the event of an engine failure. I also don't see why, in your scenario, the climbing/level aircraft would, de facto, be issued a Climb RA. As I'm sure you are aware, there are a complex series of interactions between two RA-enabled TCAS boxes, and the results, though always safe, are not necessarily predictable, are they ?

An RA issued simultaneously to a descending engine-out 757/A321 and a climbing ATR would, as far as I understand it, be more likely to ask the jet to climb or monitor vertical speed, as the boxes would have agreed the jet has better performance available.

With your box selected to TA, the ATR would get a more appropriate RA as the ATR system would be aware that no resolution would be issued to the jet.

Very interesting topic this, and this is only my understanding of how the kit works. Wonder if anyone knows any better !

13th Mar 2003, 09:16
Ghost, if you think all ATC need is 30 seconds to clear a safe path in this day and age, then its time to cash in your next Centre Visit ticket. Fair enough we can start the avoiding action rolling, but in a stack system?????????? Remember that avoiding the emergency a/c has EXACTLY the same priority as getting the others to still avoid each other too, even if reduced separation has to be used :)

13th Mar 2003, 09:49
ref 126.7 ;if he is going to treat me like a 5yo, I'll do the same for him. Honestly, it doesn't take too much effort to read the thread thru and be able to follow the discussion.

Re TCAS; I looked at as much info as I could on the subject after Bodensee, and I learned a lot. One of the most important things I learned is that a lot of the participants (pilots and ATCers) don't have a good grasp of the various systems. (not everyone agrees on whether an RA supersedes an ATC instruction- ask a Russian (and there are plenty of them flying around)). You seem to believe that you wouldn't get a climb RA when descending one engine. I believe your chances are 50/50, but I'm willing to hear any arguments:cool: . I didn't know that it's your SOP to switch to TA (but how would I?- another failing in {recurrent} atc training, knowing what sort of things are in the checklists). Is that common?
Another misconception; do you expect me to notice you in unauthorised descent? I may, or I may not (the older equipment I work on doesn't have automated alarms for things like track-keeping, altitude-keeping etc). So you better rely on your call to me to alert me to the fact. When will that call come? Not amongst the first few items I would guess. How many 000's of feet would you be down before it happened? What about the traffic 1000' below? What if you can't call immediately/get stepped on?
Lots of things to think about- not the least of which is the (yet another) TCAS issue.

13th Mar 2003, 09:59
You would be surprised how many ATCers dont know didly about a/c. Plenty dont know that a twin cant maintain cruising level with one engine out.
Its mostly due to a lack of interest and virtually no contact with the flying types. Sad but true...

Jump Complete
13th Mar 2003, 12:01
I declared a 'MayDay' last year (flying a parachute aircraft) It wasn't a engine failure (that would have been less frightening than the situation, and I was flying a single!) Once on the gorund safely and when one has calmed down it is easy to then think a 'mayday' wasn't required. However, I reported the problem initially and had to repeat it twice without much understanding. So I declared a MayDay. The aircraft was in danger, even if not 'immediate'. I did get assistance that helped me resolve the problem but there really wasn't a lot they could actually do for me and when they said "Roger, ....., what assistance do you require?" I thought..Good question, what the hell can they do for me?"
However, without the help they gave it might have turned out a lot worse."
Thanks guys! (Lakenheath Radar!)

On the subject of the incident being discussed, I would have thought a 'pan' would suffice if the aeroplane can maintain hieght and a 'mayday' would be definetely required if it was descending regardless off what was underneath.
I don't understand why a aircraft underneath would be get a TCAS 'Climb' resolution to avoid an aircraft descending from above?

13th Mar 2003, 12:47
Nigelondraft good summary

There is an awful lot of discussion and opinions here, so I'm just doing a double check on what I've got so far.

In the event of an engine failure

1) A Mayday call is the captains call, complemented by operator SOP's

His considerations are based on

a) Annuciated effects (fire, decompression etc.)

b) Aircraft performance vs commanded thrust (ability to hold altitude)

in this case he probably didn't lose 50% of available thrust, since he is not at max performance conditions

c) Potential ATC issues affected by reduced performance


Anthony Carn
13th Mar 2003, 13:07
I suggest "MAYDAY" every time if in any doubt, then details, then "STANDBY" (very useful word, STANDBY) if all you (the pilots) want in response is brief acknowledgement and then silence.

The point I'd mainly like to emphasise here is that dealing with an ATC query is only a small part of the problem -- the biggest side effect is a break in one's train of thought and a breakdown in pilot-to-pilot communication and co-ordination. One often has to start a task all over again, or one forgets to return to the task in hand before the call, probably because another task is by then demanding one's attention. A snowball effect can soon be established, from which there is no recovery, all set in motion by an apparently simple r/t call !

The pilots are also potentially under verbal assault, to a variable degree, from cabin crew of VASTLY varying ability/common sense (IMHO). That aspect bothers me, sometimes.

It's all about workload and giving the pilots a chance of coping with it.

13th Mar 2003, 13:44
Which is precisely why when you do call, you will just get an acknowledgement. We are trained not to ask or do anything to you. We realise that your workload is now very high. Rest assured, if you're dropping straight into someone else, I will be talking. We also have a lot of things to do off R/T.

Couldn't agree more about calling it a mayday first, then downgrading if warranted. It may be that call which makes someone in another cockpit sit up and pay attention (and get out of the way/stop talking over the top of you/ etc)

Frightening, the faith people have in TCAS.

13th Mar 2003, 19:33
TCAS does not know which type of aircraft it is attached to.
TCAS does not know how high you are flying.
TCAS does not know about the performance of the aircraft.
It may ask you to climb when you are flying at your maximum altitude. It may give you commands to climb at a higher rate than you are able to.
TCAS does not know if you are flying on QNH or STD. It uses STD.
TCAS does not know which altitude you have set for level off.

TCAS does know your altitude relative to that of other traffic, and the closure rate. It will coordinate evasive action between you and another aircraft.
Setting TA ONLY in an engine failure situation will inform the other TCAS that you will NOT be able to make any evasive maneuvers, and the other aircraft will receive commands based on this. Smart thing to do.

14th Mar 2003, 08:13
First, may I offer Faustino's rules of thumb?

Mayday - if the successful and safe outcome of the event is in doubt.

Pan - assistance and/or priority is required but the event will be safely concluded.

So, engine failure - Pan, reverser unlock in flight - Mayday.

Another way to think about it is: Is the situation stable or unstable, and is it life-threatening or not? If non-life threatening and stable, Pan; if either unstable or life-threatening (or both!!), Mayday.

My exception to this is that in any state bordering the Med, I would never use Pan. I know that Pan calls have been ignored in at least some of these states and base my opinion on this knowledge.

I'd rather not read bald statements about this being the 'Captain's call'. The Captain may initiate the judgement, but should definitely consider the views of the other crew members in the flight deck.

Onto TCAS, I have no problem with opinions being offered here, but they should not appear as facts. TCAS is massively misunderstood by pilots and ATCOs alike. Some of what ManaAdaSystem says is correct, and some is wrong. Anyone like to guess which bits are which?

ferris, in law, an ATC instruction has precedence over a TCAS RA. (Tokyo convention). Wait and see who carries the can for Bodensee before we draw conclusions. A Commander who disobeys an ATC instruction in order to follow an RA assumes responsibility for the safety of his aircraft and absolves ATC of their element of such responsibility.

Johnny F@rt Pants
14th Mar 2003, 08:23
Back to the aircraft involved, I was back in BCN yesterday and it was A320 G-SSAS and the engineers were working on the right engine with a new one sitting on the ramp next to the aeroplane.

Somebody said earlier about this becoming another Airbus-Boeing thread over this, why should that be, it was the engine that gave way, not the airframe.

14th Mar 2003, 08:37
<<First, may I offer Faustino's rules of thumb?

Mayday - if the successful and safe outcome of the event is in doubt.

Pan - assistance and/or priority is required but the event will be safely concluded. >>

I'm afraid to disagree. There are ICAO definitions of these words, and they differ from yours in some specific circumstances (one of which we are discussing here).

Back to first principles - why are we using the pro-word? It has nothing to do with the Flight Crew, their actions, or even the danger they face. It is to do with the level of assistance you, as Flt Crew, require, and the consequences of not getting it in the timescale required... All very neatly covered in the ICAO definitions...


14th Mar 2003, 10:19
OK Ghostflyer and anyone else interested in this thread:

Do you see where I'm coming from about lack of understanding of TCAS and the rules governing it?

Faustino; did you get what I meant when I said I believe that when you (rapidly) descend without clearance, you are quite possibly in 'grave and imminent danger', thereby warranting a Mayday? And out of interest, what company do you fly for and what is their SOP for TCAS RA? After Bodensee I asked a straw-poll question on this subject (in the aircrew questions forum), and every reply was that "we follow RA over ATC" (as far as was disclosed, all these responses were from US or 'western' carriers).

I had hoped some lessons were learned after Bodensee. Obviously not.

ps In the UK, US, Australia and the UAE (these are the places I have actually checked the rules), you are expected to follow an RA over an ATC instruction (although, possibly ambiguously once again, the rules are phrased with 'should' rather than 'shall').

edited for spelin

14th Mar 2003, 11:37
Something that doesn't appear in this discusion, but I think should, is changing squawk to 7700 - particually if your emergency is going to result in an immeadiate deviation from your cleared flightpath or level.

As an ATCO I have never seen the squawk changed on pilot initiative in an emergency, only when instructed by ATC. Does it appear nowhere in the emergency check list or is SOP to wait for ATC instruction?

In the context of this thread, squawking 7700 coincidently with making a MAYDAY call, helps ATC hugely with our response as it alerts all sectors, not just the one you're talking to.

14th Mar 2003, 12:48
Good point Arkady.

The only place where it (7700) is written is in our emergency descent procedure.

As to "spot the errors" in my TCAS post, I would like to point out that TCAS indeed knows what FL you are flying at, but it doesn't care. It may issue a climb RA when you are flying at max certified altitude.
It also uses Radio Alt when you are operating near the ground, but may still issue a descend RA into the ground when you are flying over terrain.

Declaring an emergency is the commanderís decision. Thatís the law, at least where I am. If he is smart, he will use all available resources before making that decision.

14th Mar 2003, 13:11
Faustino you said

........assumes responsibility for the safety of his aircraft and absolves ATC of their element of such responsibility.

I could have sworn that I have responsibility for the safety of any aircraft that I am in command of from the beginning to the end of the flight.

If I get a TCAS RA rest assured I will be following it unless I can see a very good reason not to!

14th Mar 2003, 17:49
M.Mouse, Faustino didn't quite get the wording right. In my land, you are expected to follow an RA when issued, and then become solely responsible for separation in every class of airspace, absolving ATC of any direct command or responsibility. We are taught to pass traffic only if though pertinent, otherwise 'Roger' the call and await 'clear of conflict, returning to level...' whereby we again announce you under a Radar Control Service (if applicable). Yes you are right by saying "I have responsibility for the safety of any aircraft that I am in command of from the beginning to the end of the flight.", however part of this is OBEYING an executive ATC instruction inside CAS, and informing if unable to do so stating a plausable reason. I agree following an RA is definately the best action in todays world, but in certain places it could get very lonely when all the separation becomes your responsibility, we'll do our bit, but how much can we do????

14th Mar 2003, 18:49
Fair dinkum, how simple could this be. Either everyone follows the RA, or it's a waste of time and a recipe for disaster.

5milesbaby, Faustino and others
Page 4, para 3.5
A pilot faced with conflicting instructions from a controller and an ACAS system should follow the ACAS advice.

Departure from ATC Clearance
The commander of an aircraft is permitted to deviate from an air traffic control
clearance for the purposes of avoiding immediate danger [Air Navigation Order 2000, Article 84(3)(a)]. Response to a Resolution Advisory comes under this heading and is not, therefore, a breach of Rule 31(3)(a) which requires conformity with the clearance. The commander is required to notify the air traffic control unit as soon as possible (Rule 31(4)) and submit a written report within 10 days (Article 84(4)).

UK MATS Part-1
Effect on ATC Operations
The effect of advisories on air traffic control operations is as follows:
Traffic Advisory - Pilots are advised not to take avoiding action on the basis of TA information alone but may ask for traffic information.
Resolution Advisory - Pilots are expected to respond immediately but have been instructed to restrict maneuvers to the minimum necessary to resolve the confliction, advise the air traffic control unit as soon as is practical thereafter and return to their original flight path as soon as it is safe to do so.

Need I go on? All this is available on the net.

14th Mar 2003, 18:53

Good point. However, I believe I was taught that if you are receiving an ATC service with a squawk, one should keep it in an emergency unless ATC ask you to change it. You only self select 7700 when without a service. That's the theory...

However, within my limited understanding of ATC systems, I believe the filters on your radars are such that you only see "your traffic" / area/ FL band. In case of an (uncleared) emergency descent, 7700 will show me on EVERYONE'S scope, and is thus a good idea...

More input welcome on this...


14th Mar 2003, 19:14
Putting 7700 on the transponder is fine in theory, but - "when you are up to your ass in alligators.......". I think most of us will put 7700 on when we get round to it, but the R/T call to ATC will come a few stages before we do it unprompted.

El Desperado
14th Mar 2003, 19:57
Mana - sorry mate, you are not completely correct with your TCAS info. It may well be the kit fitted to your aircraft, but ours will not issue a descent into terrain (no RAs below 1450ft and GPWS takes precedence over TCAS in any case), nor will it demand a climb above max available FL.

Max available FL is dependent on weight on heavy jets, and our system feeds the max available perf. into the TCAS kit - it will not demand an RA that cannot be complied with.

The only problem it has is with the engine-out scenario - the FMC and other systems do not feed TCAS that info and it still assumes max perf. available.

14th Mar 2003, 22:28
Good discussion!

ferris, 'should' does not equal 'must'. You will find the word 'must' absent from TCAS operating instructions as legislation takes no account of TCAS nor places any responsibility on pilots to obey it.

5milesbaby, I should have been more specific. A better way of putting it is to say that a pilot who follows an RA and has a collision is very probably responsible, in law, for the collision. In CAS, the law requires you to obey ATC instructions (in broad terms).

M.Mouse, same point. And no, you do not have ultimate responsibility for safety. You or your company share that responsibility with, for example, their regulator, contracted providers of training and maintenance, parts suppliers, refuelling companies, airport authorities... need I go on? Your company audit most of these risk-sharers, but not ATC. I'm sure the DHL crew would have shared the sentiment in your final sentence. None of the publications you mention are Statute Instruments. None of them say 'must'.

NigelonDraft, I only offered an opinion!! It works for me and for colleagues, especially when analysing incidents etc, and no rule of thumb is bulletproof. Your point about emergency SSR codes forcing targets/tracks through filtered displays is a very valid one.

ManaAdaSystem, if you are at max certified altitude and receive a 'climb' RA there is nothing wrong with following it provided you do not bank significantly (max, say, 15deg AOB). Certification limits are not an issue and you need to understand the manoeuvre limits at certified ceiling (and at V2, V2 +15, etc).

I'm giving more thought to ferris' other points. I fly for a major European airline and our SOPs reflect the state of the legislation and advice.

14th Mar 2003, 23:18
Just for anybody who is interested in the engine type, if it was indeed G-SSAS then that a/c is an A320-231 equipped with IAE engines. Not sure if the whole MYT A320 fleet is or not.


16th Mar 2003, 00:20
Frpm an ATC point of view on this, when an aircraft declares and emergency be it a PAN, MAYDAY or a WE'VE GOT A PROBLEM, we have set procedures ( a checklist that we have to go through):

1. POSITION, inform the pilots of their position and advise nearest suitable airfields.

2. PERFORMANCE: How is the aircraft performance affected (i.e loss of an engine = direction of turn)

3. INTENTIONS: Ask the crew their intentions

The list goes on to subjects such as what help we as controllers can give, changing to a discreet frequency/ clearing the frequency.

However the last point is NEVER assume the crew are too busy to talk.

I've dealt with many emergencies in my time as a controller and I've only ever lost one aircraft.

We will do everything in our power to get you on the ground safely (moving heaven and earth if necessary along with all the other aircraft in the hold below you if an emergency desecent is required)

There are lots of things we need to know (for the emergency services) therefore we will need to ask questions, if you're too busy then a STANDBY will suffice, but dont forget about us, I had a crew with a u/c problem declare a mayday, asked me to standby and then promptly flew outside controlled airspace at a NON terrain safe level (after I'd asked them to climb).

Were here to help!!!!!!!!!!!!!

As an aside, since we're not allowed flight deck / js rides anymore, how about simulator visits when you guys do your checks????

16th Mar 2003, 05:56
Faustino: TCAS not accounted for in legislation? None of the docs mentioned are 'statute instruments'?
You better stick to flying, as your lawyering sucks. Where do you think the power to create the ANOs, Rules Of The Air etc comes from?

You are quite correct in saying 'should' doesn't equal 'must' (or 'shall'), I had already pointed that out in an earlier post. The reason the imperitive is not used, is to allow the crew discretion in taking avoiding action. eg if you visually aquire the traffic and elect to turn to avoid, rather than climb or descend as per RA. If the imperitive was used, then you would be committing an offence automatically and axiomatically by not following an RA. Avoid the accident, but still get charged- not ideal.

I disagree that a pilot following an RA and has a collision is responsible at law. That is your opinion, and not a fact. IMHO, a pilot who follows an ATC instruction and has a collision will, ultimately, bear some of the responsibility (at law).

Bottom line. A lot of time has passed since Bodensee, and still the confusion about TCAS, RAs, hierarchy of responsibilties and priorities etc abounds.
A lot of US and UK pilots staunch in their conviction that they will follow the RA, no matter what. Not going to help you one bit when you smack into Faustino or his 'large European carrier' buddies.

16th Mar 2003, 11:14
"Should" is wishy-washy

"Is most heavily recommended" is the terminology I would use here - why, you are not automatically in breach, as you would be with a "must", but it should be clear to all that way that - unless there is a most compelling reason not to, such as "can't for some overriding reason - YOU WILL.

As an observing PAX - this is one of the best threads for a long time guys.
Getting it out on electronic paper and talking it through has got to help make the right conclusions work their way through.

Cross-over training seems to me to be a most advisable way to go - and ATC's MUST be allowed jump seat as part of their, out of scope, training (sorry could not resist that one) - and off duty pilots - fix to see your friendly ATC's.:ok:

16th Mar 2003, 13:13
I seem to remember a 146 declaring a PAN call in Spain a few years back and it caused total confusion with ATC.

16th Mar 2003, 19:45
This is a great thread, and I would hate it to become less than that because of any aggressive words used. However, I would like to continue in the debate.

ferris and I obviously have some different ideas. But, I would ask ferris which of the documents he referred to are SIs. Yes, the power to create those documents and to impose restrictions of flying etc are ensconced within SIs, but the content of the documents mentioned does not amount to Law. My experience of prosecutions in the UK indicates to me the importance of comprehending this. I am also at a loss to know where I might find a piece of legislation about TCAS. If anyone wants to prove me wrong, please post detail!!

Regarding liability, regular briefs on the Bodensee accident from two of the investigation organisations involved come my way. May I invite ferris to wait and see where the blame is placed by the courts and who pays out before we decide what's going to be what.

The perceived allegation that I would not follow an RA is without foundation. I will do whatever is most likely to ensure the safety of my aircraft at a given time.

The fact is, TCAS is not a perfect piece of kit, and it is interesting to note that many TCAS events are not correctly dealt with by flight deck crews. Misuse of TCAS can make it a collsion guidance tool.

17th Mar 2003, 14:19
To pursue the matter of TCAS useability with an engine failure, here's what Gulfstream told us on my (recent) G5 initial:
TCAS is fed with "standard" performance specs for the airplane you are flying, ALWAYS assuming all-engine. When in conflict with another airplane, both TCAS also "exchange" their aircraft type. Due to the very high performance of the G5, and if a resolution advisory occurs, the G5 will get the "CLIMB CLIMB" end of the deal.
Accordingly, one item on the "Engine failure in flight" checklists is the switching of the TCAS to "TA only". This will not only prevent our own aircraft from displaying RA's outside of the envelope, but it seems (instructor said so...) that the box will actually transmit the fact that we are in "TA only" mode. What I don't know is how that transmission could or should affect the other party in the conflict...
Anybody know more about the intricacies of TCAS in these situations?

17th Mar 2003, 15:46
With TA only selected the "other" aircraft assumes worst case and gives instructions to climb or descend depending on altitude, ROD or ROC etc to deconflict. After an engine failure TA Only is a good airmanship decision - of course there may be situations that would not be suitable but i wont labour the point here. Suffice to say that if you don't you may get a "Climb Climb" RA which you may not be able to correctly follow.

17th Mar 2003, 18:20
Faustino; first, lets get the legal wrangling out of the way. I asked a real, practising lawyer for a definition of Law, Statutory Instruments etc. Here is the reply

"Generally speaking:

- the term 'Law' refers to all forms of law, including legislation
passed by parliament (Acts), statutory rules (which derive their power
from legislation), common law (laws that derive their power from
precedent and have been passed down through the ages, eg negligence),
order-in-council, constitutional law, by-laws etc etc.

- the term 'legislation' refers to the Act itself. For example, the
Air Navigation Act may empower a particular office-holder to make
certain rules. In this case, the Act is the legislation and the rules
are statutory instruments."

So TCAS is addressed in 'Law', by Statutory Instruments. See ealier posts.

Back to the main problem:
TCAS RAs and the situations when they are required, are time critical. You must act on an RA within seconds for it to be effective (I believe 5 seconds is the standard?). When you make statements confirming that you may or may not act upon an RA, you are condemning the system to failure. RAs require an almost blind obedience. You have already had 45 seconds (the TA) to assess the threat, get it visual, seek ATC guidance, whatever. An RA means it is out of the controllers' hands now. As I hope everyone is aware, the system is flawed. But if everyone is not on the same page vis ground rules ie. everyone follows the RA, then we are setting ourselves up for another Bodensee. And that truly is a tragedy.

ps. if you think some blame apportioning at Bodensee will help your arguments- well, what can I say? Why don't we think in terms of learning and fixing, instead of blaming?

17th Mar 2003, 19:56
ferris, yes, let's stop wrangling. We disagree about the legal position on TCAS. Many 'experts' I talk to agree with my view - that's how I arrived at my view in the first place! But, let's not fall out over it!

Now to the nitty-gritty: You will not get a guaranteed 45 second TA, especially with v7.0 - it may be much shorter. See Prof. Peter Ladkin's paper on RVSM vs TCAS and the Safety Case for details of how v7.0 may be a step backwards.

You mention 'learning and fixing, instead of blaming'. I am wholeheartedly behind you, and my day-to-day work centres on just this!!!

My point is, that until legislation/law/SI/whatever you want does properly take account of TCAS, then it is at worst a loaded gun with someone else's finger on the trigger.

It is at best an elastoplast, an ambulance at the bottom of a cliff, an unreliable last line of defence. The whole industry has tackled TCAS from the wrong angle. That's why Bodensee happened.

Please, let's all try to keep the safety ball rolling, with the best genuine intention of ensuring the last mid-air was the last mid-air.

Sadly, it won't be...

17th Mar 2003, 21:21
So what is your proposed solution?

2 six 4
19th Mar 2003, 10:14

You would be surprised how many ATCers dont know didly about a/c. Plenty dont know that a twin cant maintain cruising level with one engine out.

ATC knowledge about aircraft performance is rudamentary. Unfortunately any background lectures on aeronautics were abandoned long ago. We really should know more about aircraft performance as it is constantly changing. For years ATCOs were encouraged to take 2 familiarisation flights a year and get real line cockpit experience. Then we were privatised and guess what ... we were short of money so the first thing to go was this sort of "unnecessary" expense.

Still, in 30 years I have known hundreds of ATCOs doing their best to gain knowledge by going on these flights. Very few pilots have shown an interest in learning the ATC side of things which is why you get the sort of comments made by Finbar which are made through ignorance of the real story. ;)

limaeco An excellent post. We appreciate what you were doing.

Nice to see PPrune returning to some interesting professional points. :D

19th Mar 2003, 13:12
Very entertaining discussion. A few points from my side of the world, that is Texas;

Whether the pilot says "Pan", "Mayday", or "Blueberry"; if I know the aircraft has lost an engine, ATC will treat that aircraft as an emergency, unless there's a very good reason known to us not to. Obviously, we're going to be taking clues from the crew's requests and tone on the radio as to how much Immediate assistance is required.

As for the remarks about controllers not knowing much about aircraft performance; while It's obviously been more difficult and expensive to obtain pilot ratings/experience in other parts of the world, I presently work with, or have worked with:

Retired DC-4 thru 727 Captains
Decorated Air Force Pilots from WWII thru Vietnam and later.
Decorated Vietnam era Army Helo pilots
Controllers with type ratings in Lr-25, Hawker 125, etc.

We currently have about six Flight Instructors at my facility, and at least another half dozen with FAA Private/Commercial ratings.

The above list comes from just two medium sized Terminal facilities. Were you to canvas a Center, with 400 some-odd employees, God knows how many former/furloughed airline and corporate pilots you'd find. :eek:

And I myself am a CFIIMEI with Corporate experience (albeit many years ago) on the MU-2.

The truth is, none of us have training in mental telepathy, as someone noted. In an Emergency, tell us what you need, and we'll do our best to see you get it.

Shock Stall
19th Mar 2003, 21:19
This is a great thread, Itís got me thinking!

Back to the 7700 argument,

We (bus drivers) all spend most of our time in the sim practising engine failures on approach or on departure when 7700 is pointless as control know who and where we are, and in the case of departure have just given us a code and are waiting for us to call them to verify our altitude. It is assumed that an engine failure on approach or departure are the most difficult to deal with and if we can handle that, we can handle one in the cruise. This is true BUT there are many new factors in an engine failure in the cruise that are not considered for approach or departure, one of which is 7700.

The ATC guys have been quiet on this one. Is it true that you are filtered and that 7700 shows up on all of your screens? Do you expect us to change to 7700? Do you want us to? I donít know what our SOP is for 7700 use. Iíll look it up now (man I hate those binders!)

I do know our SOPs say engine failure = Maday. No decision to be made. Many of you were right in saying that you have suffered a 50% power loss, BUT you have also lost 80-90% of your performance (time to pull out those flight manuals again lads!). That kind of performance degradation is a Maday call, every time. You ARE coming down, I wouldnít even downgrade to a Pan on approach, what If you miss the approach? Itís a long slow climb away from the ground!

Itís been great getting the ATC input here Ė Keep it coming! This is exactly why we need cross over training, we need to understand each otherís jobs. We spend all day talking to each other, and we need a good understanding of what the other does. Why is a controller allowed to tell 10-13 aircraft what to do when heís on the ground, but suddenly becomes a security risk and a danger to safety if he sits in the jumpseat?

Iím not trying to re-open this debate, but is the jumpseat going to become somewhere to keep our emergency sandwiches and coffee for those occasions when we piss the Cabin Crew off and they ignore our calls for sustenance? ;)

19th Mar 2003, 22:40
In London airspace currently controlled from Swanwick, some sectors are permitted to operate with filters, but the majority aren't. It is certainly true that by selecting 7700 you will break through ALL filters and be displayed with a red alternating yellow flashing box around the Datablock associated with the return. There is no mistaking an emergency squalk. Also by selecting an emergency squalk, an alarm bell sounds inside the Diversion/Distress cell at West Drayton monitoring 121.50MHz. This however differs in Terminal Control still at West Drayton, as the Datablock loses its callsign information for it to be replaced by 7700, but still it breaks through the filters.

As a controller receiving such a 'Mayday' call as this one, I will automatically in first reply say, 'Roger Mayday, when able squalk 7700'. Every time. If you ever think you are too busy to call ATC, then definately just select it ASAP so at least we know you have a problem. It will certainly lead us to instantly calling you and imposing an RT silence, but what else would you expect? I highly advise against this practice though, and should NEVER be too busy to call ATC, there is just too much going on out there for it to be safe not to.

Mac the Knife
20th Mar 2003, 18:08
Given the close interaction and interdependence I guess I'd sort of automatically assumed that ATCO's and pilots had some sort of cross-training. Theory, ATC visits, jump-seats, sim stuff and so on for both.

As it emerges, you don't seem to much and from the sound of it, it would help a lot with understanding, cooperation, tempers and, dare I say it, safety.

So why isn't there more X training?

[Modbod - should I re-ask this in the Questions forum?]

West Coast
20th Mar 2003, 18:53
TCAS or ATC.....

If its to the point of a RA, likely my primary means of seperation, eyeballs and ATC have failed. Its now time to to listen to the box which is not under the stress a controller might be at that point. By that point the controller is no longer planning, just reacting.

To mayday, or not to mayday...

Depends on type of engine failure, associated failures, location, atmospheric conditions, weight and numerous other considerations. Numerous aircraft have certain engine out procedures in the abnormals and not the emergency sections of the books.

20th Mar 2003, 20:26
I personally experienced 2 TA's, on one I've never seen the intruder despite looking out and not IMC and on the second one we saw the intruder at the very last time (it was a light piston-twin) and it was also IMC,

these to say that:

1- According SOP's we must follow any TA

2- It is nice to look outside, but as you know, sometimes it's very hard to pick an aircraft doing the approach just in front of you!

3- It is working only if every body do the same ( look at Bodensee)

Mayday vs Pan Pan:

When dealing with a threatening failure, engine, flight control, structural damage, smoke-fire) one is flying, navigating and radioing, the other is doing the MC's, then we should return to normal loop (extended) and assess the situation? right, then you choose to decalre an emergency perhaps with the mandatory reports, 7700 and TA only, so it is likely that you started to descend a bit already! Not easy when under pressure to think at all those things together and not missing a part...


ECAM Status
20th Mar 2003, 21:53
My company's SOP's state that an engine failure is definitely a Mayday Call. That is for many reasons some of which being: Unable to maintain altitude, what happens if you lose the other engine as well etc. For the Bus drivers, don't forget the RED LAND ASAP memo on the lower right corner of the E/WDisplay.

When it comes to TCAS RA's while you are on single engine, my company's QRH in the engine failure page, says to select the TCAS selector to TA's ONLY, so that not to be given RA's that you may not be able to follow.

I also believe that instead of starting Airbus Vs Boeing arguments it would be better to say well done to the guys that landed the plane safely and saved lives.

21st Mar 2003, 17:26
Is there anyone out there willing to step forward and say that their SOPs, local laws (or the widely held interpretation of said laws, either by unions, pilot bodies, personal opinions), or beliefs are to follow an ATC instruction in contravention of an RA?
Please add as much about where and for whom you work as you feel comfortable with.

This is not a slag-you-off session. Just trying to gauge how much variety/confusion really exists out there.

ps. not all controllers are ill-informed halfwits when it comes to a/c.

pps. a/c can also mean air-conditioning:}

21st Mar 2003, 18:18
Can the controller declare an emergency too? I overheard an exchange where a water cooled light piston had dumped it's coolant over the side over mountainous terrain. The VFR pilot was not keen to say MAYDAY or even PAN (which is not even taught in the USA). The pilot was obviously not a "professional", whatever that means :), and maybe that was very relevant to what happened.

The controller eventually said something to the effect of "XXX Approach is declaring an emergency. NXXXX squawk 7700, cleared into the XXX Class B, if able maintain altitude and turn right heading 270, contact me on xxx.xx, etc etc etc"

So although he could not force the pilot to say MAYDAY, the controller was able to escalate things to "emergency" and get the ball rolling so he could make things happen. This was in the States and the plane landed safely.

21st Mar 2003, 21:46
If you have an engine failure there is no doubt you should declare a Mayday in my opinion, I would also squawk 7700 when time allows, I want to make sure I get all the help I can!

The USA is not the only country that does not recognise PAN, try using it in Spain and you will be met with a stunned silence or asked to say again! My view is if you need to declare a PAN outside UK airspace say Mayday and explain later.

With regard to TCAS being set to TA after an engine failure the Airbus FCOM 3 drill ďafter ENG 1(2) failureĒ instructs you to select TA. I canít recall what the Boeing or MD manuals say and they are tucked in the loft somewhere. I would say setting TA after an engine failure seems like good airmanship to me.

As for ATC not understanding performance that may be true to some extent but as has been pointed out many controllers are also pilots. That said I canít see why it should cost NATS any money to let their controllers fly on the jump seat. After all most of the larger UK airlines are part owners of NATS so in a way UK controllers are to some degree company employees! Certainly I have taken controllers on the jump seat in the past and my company has not charged NATS for these familiarization flights.

I have long felt it would be worth investigating getting controllers in the Simulator for day two of an LPC/OPC; we do it with cabin crew. I certainly found visits to West Drayton and Prestwick very useful, especially the hour I spent on the ATC simulator, three-dimensional chess! I found the experience gave me an even greater respect for the job UK controllers do.

22nd Mar 2003, 02:41

In the U.S., the crew, the controller, OR the Operator may declare an emergency.

Anyway, most of the firefighters I know say they rather enjoy the practice of setting up on station alongside the runways;

(Unless there's a good football game on of course....) :=