View Full Version : Emergency Descent, 90 degree turn?

16th Mar 2002, 05:01
I've just done an training module where it was claimed that the first thing (after putting on. . the oxygen mask) a pilot will do is turn 90 degrees off track (unless in a holding pattern). . .. .I was aghast I could play in this wonderful industry for this long without knowing this, but it seems a bit unlikely. Can anybody confirm this procedure?. . . . <small>[ 16 March 2002, 00:03: Message edited by: Spodman ]</small>

16th Mar 2002, 07:01
There is a bit more to this than that. It would be wiser to instruct to turn into the most favorable direction. On top of that, with TCAS, we have the possibility to see other possibly conflicting traffic.

16th Mar 2002, 08:53
I've seen many different types of procedures for the emergency descent. Two reasons for the turn include getting off the airway or track, and/or to keep a positive 'G' load on the airplane during the initial push over.

16th Mar 2002, 09:58
The generic way is to roll the aircraft either right or left to forty five degrees of bank, all the while reducing power and operating the speed brakes/lift dump. Allow the nose fall through the horizon to about twenty degrees or so nose down, level the wings and let the airspeed to build to MMO/VMO. As yxcapt says, the roll will apply positive G and turn you off the airway. If you suspect structural damage to have occurred, you may want to carry out the descent in a high drag/low airspeed configuration. In that case in addition to speed brakes add the gear and flaps and instead of MMO/VMO descend at the maximum IAS for the configuration.. .Different aircraft types no doubt have different procedures, but with minor variations the above one is pretty general.. . . . <small>[ 16 March 2002, 05:02: Message edited by: pigboat ]</small>

16th Mar 2002, 20:49
A well-established procedure. Far less likely to hit something on the way down when you are outside the airway than in it with levels below you allocated?

16th Mar 2002, 21:24
It most often is not SOP, but merely airmanship. No one would sink through many flightlevels in a congested airway. Only country I know of where it is mandatory to turn off the airway, is Russia, where you have to make a 30deg turn to your right.

17th Mar 2002, 03:00
Practically, the best thing to do (in a radar environment), is to make your RTF call:. .. .'Pan Pan Pan, London Control, Bloggsways 123, emergency descent, descending FL100, we can fly radar headings'.. .. .This will enable the controller to shift you away from the thirty aircraft under you, rather than the thirty aircraft away from under where you're going. Especially important where those aircraft are under control of another sector.. .. .Also, in an SSR environment, squawking 7700 will 'force' your datablock through onto the displays of the controllers working airspace under you, who have height filters on to display only their traffic (and a bit more, vertically speaking), thus enabling them to see you coming before you plummet into 'their bit' (technical ATC term) at 6000fpm plus.. .. .Perhaps a couple of current ATCOs could back this up and add to (or even subtract from) it? (eyeinthesky, where are you when I need you?). . . . <small>[ 16 March 2002, 23:08: Message edited by: NorthernSky ]</small>

17th Mar 2002, 10:56
It's one of those things you can use to amuse your mind as you fly along on autopilot. Just as in light singles, you may have looked out of the window to spot suitable forced landing sites, in an airliner you think about safe directions to fly should you have to perform an emergency descent, along with the drift down altitude you will require in the event of an engine failure.

17th Mar 2002, 14:06
Northern Sky - thank you for your input - worth progressing and perhaps it needs reviewing. The only caveat I would place here is that we (flight crew) have to think about operating in many FIRs, not just UK, and without being unkind... well...........

17th Mar 2002, 14:23
BOAC,. .. .Quite right. When flying into unfamiliar FIRs, I review the appropriate procedures coming up to the boundary, and have the charts to hand.. .. .A couple of points: First, be wary of making that turn to clear the airway if it will take you into a danger area or military training area or what-have-you, second, I would think that in a busy CTA (Daventry, for example), a ninety degree turn without instruction to do so could put you well and truly in the brown stuff.

17th Mar 2002, 20:38
this is standard procedure when flying nat-track routings if you require rapid decent. due to the absence of radar this procedure instantly seperates you from all other traffic.

Young Paul
17th Mar 2002, 20:42
I think in either RVSM or MNPS, the turn off track is mandatory. Can somebody shed light on this?. .. .As for the "generic" emergency descent, it certainly isn't the specific one for B737 or A320. Furthermore, if structural failure is suspected, speedbrake and acceleration are discouraged as well.

17th Mar 2002, 23:24
The airspace over the N-Atlantic is RVSM, so it is both MNPS and RVSM. As most planes crossing the Atlantic fly the precribed tracks (A,B,C,D and so forth) and the tracks are seperated by 60 NM laterally and 1000' seperation vertically on a same track it is recomended to turn of the track during emergency descent and the fly offset by 30 NM. This should keep the troubled aircraft away from other traffic as there is no radar coverage over most of the N-Atlantic (except from the Faroe Islands, Iceland and Greenland).

17th Mar 2002, 23:58
I`ve nerver been told to turn while starting descent unless you`re in NAT airspace, turn 90 and offset by 30 NM. . .. .But over europe in our sims we`ve always been told, not to turn unless instruted by ATC to do so, and you can indeed turn without letting ATC know, in case you know there is traffic bellow, or congested airway and no other airway or traffic to the side, weel... GOOD CAPTAIN JUDGMENT!!! <img border="0" title="" alt="[Roll Eyes]" src="rolleyes.gif" /> But first have a look to the TCAS and see the traffic and have a tought about the terrain, look to the charts or enquire ATC. . .. .Turning while putting the oxygen masks on, <img border="0" title="" alt="[Confused]" src="confused.gif" /> is against safety. Acording to the Boeing FCTM (I don`t know the airbus procedures) you put the oxygen mask on, talk to your partner to see if he is ok (bad time for a pilot incapacitation) and then analyse... structural damage or not? Only after that you can start the descend and turn wherever you want! . .. .Cheers <img border="0" title="" alt="[Wink]" src="wink.gif" />

manuel ortiz
18th Mar 2002, 00:47
Spodman ,. .. .Now , don't consider the turn as your only option.. .In some cases you may have the time to coordinate with ATC and staying on the airway may represent the best course of action due to terrain or traffic.. .. .An emergency descend can have different reasons and levels of urgency to be executed .. .We all know the scenario for which we train the most but you can also find yourself in a situation which perfectly allows for a more prepared and coordinated event.. .. .Rgds. .. .manuel

18th Mar 2002, 02:41
The answer to this depends entirely on where you are.. .. .If you're on an airway in one of the more distant parts of the world - NAT tracks, Africa, Siberia, Northern Canada etc etc etc - then IMHO it makes sense to turn off the airway (giving due thought to high ground etc) as soon as you can. The most likely place for conflicitng traffic to be is on the same airway as you are. As for contacting ATC first, well in some of those places........ .. .If you're in congested airspace - Europe, New York TMA, LAX TMA etc etc - then you've probably got an equal chance of hitting other traffic whatever you do - turn, or continue straight. The safest thing then, if you've got the time, is to talk to ATC before you start down (but the emphasis has to be "if you've got time"!!). .. .It's horses for courses.....

Fat Boy Sim
18th Mar 2002, 03:03
Forty five degrees of bank and nose down twenty degrees....Gulp!!!

26th Mar 2002, 14:02
Thanks for all the information. It appears almost anything can happen!!

26th Mar 2002, 15:37
Canada, also, expects you to turn to the right. See the Aerad FIS under'In-Flight Contingencies'.. .Cheers. .mcdhu

27th Mar 2002, 13:03
Turning away from any danger is the trick. NAT tracks etc have specified procedures for this.. .One skipper in our mob always briefs a turn towards the equator. When I asked why he replied; "The water's warmer.". .. .If all other things are equal... <img border="0" title="" alt="[Smile]" src="smile.gif" />

30th Mar 2002, 06:58
The 90 degree turn is (as stated earlier) required when on NAT tracks, otherwise a 45 degree turn for one minute to get away from the airway is not a bad idea.(Todays navigation is deadly accurate). The other reason for doing so is to avoid negative G's when starting the descent. As for me I would descend at the Vb (rough air) speed since it gives the best protection from high and low speed buffet, and one never knows what the turbulence is like at lower altitudes. On the A-320 it's 275 kts which at m0.78 occures at 33,000 feet.

31st Mar 2002, 20:23
I agree with the 90 deg on NAT Tracks.

Some years ago I was taught to turn 60 deg off whilst conducting an emergency descent and our SOPs still refer to using the heading bug. But, I have never been able to find reference to this heading change in any manual. Seems to me a hangup from when we were flying along airways and turning 60 deg would get you quickly displaced from the centreline. Seems a bit irrelevant these days when direct ..... seems the more usual routing and the chances of someone being below you are minimal (unless someone can let me know otherwise). However, can see some merit in reducing negative G (or less positive G!), but also support the lots of things to do anyway and adding a requirment to disconnect the AP to get 45 deg AOB seems a little like leading to getting overloaded.

1st Apr 2002, 03:17
av8er, the 45 degrees I referred to is the turn from present heading, not the bank angle. The A/P remains "on".

3rd Apr 2002, 21:34
the 45 deg AOB reference was from a previous response, no offence.