Explosive decomp
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Explosive decomp
We just had an explosive decomp in Sweden, would you as a pilot divide from your clearance? As in turning right? When would turn on 77? When would you alert me?
Just had my annual exam and I couldn't explain, because I think it's a company checklist where Pilots have more than enough to do than alert me as an ATCO.
What should I do as an ATCO?
Just had my annual exam and I couldn't explain, because I think it's a company checklist where Pilots have more than enough to do than alert me as an ATCO.
What should I do as an ATCO?
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Damn right he is going to deviate from his clearance. He needs to descend very quickly to the aircraft get into more oxygen and to relieve the strain on the structure in case anything else gives way.
If you are lucky he will have sufficient situational awareness to turn off track and descend into clear airspace but his office is now a howling maelstrom of paper cups and flight publications, so dont count on it.
I would definitely expect him to remember to squawk emergency and I would definitely remind him if I did not see it. If all I get is one shout of 'mayday' I will tag it and get busy trying to make some room.
I would then be telling my watch Supervisor/Sector Chief/anybody to spread the word for everyone to get the hell out of the way and to offload the rest of my traffic cos the emergency aircraft is now the only show in town.
If you are lucky he will have sufficient situational awareness to turn off track and descend into clear airspace but his office is now a howling maelstrom of paper cups and flight publications, so dont count on it.
I would definitely expect him to remember to squawk emergency and I would definitely remind him if I did not see it. If all I get is one shout of 'mayday' I will tag it and get busy trying to make some room.
I would then be telling my watch Supervisor/Sector Chief/anybody to spread the word for everyone to get the hell out of the way and to offload the rest of my traffic cos the emergency aircraft is now the only show in town.
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orgASMic..... great stuff. Sounds like Airplane!! I don't recall major emergencies being that exciting. Couple of phone calls... tell the Boss... sit and watch and separate from other traffic. Leave the crew alone as much as possible. Oh yes... speak at half your normal speed. Next please...
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UK guidance is DON'T turn off track as it is likely to put you in conflict with more traffic. Squawk 7700, shove the nose down and continue straight ahead. We will try to clear the sky beneath you. When you are able, tell us your issues and intentions.
The only exception to the 'do not turn' would be if TCAS indicates conflicting traffic beneath you...!
The only exception to the 'do not turn' would be if TCAS indicates conflicting traffic beneath you...!
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I beleive there is an Icao instruction which suggests pilots may turn in the descent. However in the UK most atco's would prefer the a/c to continue straight. I personally operate an expect the unexpected mentally and will keep all a/c away from one in an emergency descent as far as possible.
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To be honest i rarely see guys squawking 7700 in the simulator during that exercise and it is, together with an ATC call, pretty low on the list. Most pilots still work according to the old rule aviate -> navigate -> communicate, in that order. I do agree though that squawking 7700 as early as possible is probably a very good idea, especially in busy areas like most of europe or some parts of the US.
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would you as a pilot divide from your clearance?
When would turn on 77? When would you alert me?
Quoting Denti (my respects to you sir, btw
)
Most pilots still work according to the old rule aviate -> navigate -> communicate
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Rapid decent is best done in a spiral to prevent from overspeeding the A/C.
I experienced an explosive depressurization the year before last, involving a windscreen failure. The left side windscreen blew out, taking some of the cockpit interior with it, as well as the top of the isntrument panel and glareshield, and as luck would have it, the checklist and emergency checklist (which was on the glareshield, at the time).
After taking immediate action to ensure crew safety, the next step was to sit on our hands and evaluate. I wasn't aware of how much more damage was done. The cockpit interior panels were fractured, and the initial appearance was that perhaps structural damage was present beyond the windscreen. We had aerodynamic buffeting and noise, because much of the glareshield was outside the airplane, still attached, and disrupting airflow. I wasn't in a big hurry to do anything until I had a better idea of what was wrong. I certainly didn't want to make changes, including airspeed changes, until I knew the effect.
Generally with a rapid depressurization, after one has put on oxygen and established communications, one's next priority is to descend. Whether one departs one's "track" or not really depends where one is, and what's available. If one is on an oceanic track, one is expected to depart the track with a 90 degree turn off course. If one is flying on a domestic leg, one might make a turn to an appropriate field, one might turn back to the departure point, or one might be best to press on ahead.
The general order of priorities is always, in order: Aviate (fly the airplane), Navigate (direct the airplane), Communicate (talk).
In the case of my depressurization, I did communicate with ATC, but not until I had addressed the problem and had an initial plan in mind. At that point, I advised ATC what I had, told ATC what I would do, and made a request to have assistance standing by when we landed.
Talking with ATC and squawking 7700 both fall under communicating; important, but not the top priority in an emergency.
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I know a place (around RESMI, for those who know it), where an explosive decomp at FL370 and the subsequent emergency descent to FL100 would let the traffic cross 26 levels, a dozen flows, 4 sectors, 2 ACCs and CDG approach in 2 minutes.
In this case, the biggest problem for us is to co-ordinate with lower sectors.
When one starts the descent, we get the information 4 seconds later. If we're not dealing with something else, we'll see it straight away. Expect then ONE message (that you won't hear) to confirm your clearance.
4 more seconds later, when we see that you've lost 1000', the emergency descent becomes obvious and we begin the co-ordinations with lower sectors.
Sqwak 7700
We've got automated systems to show a traffic performing an emergency descent to sectors who wouldn't see it in normal situation (filters to avoid overflow of useless informations), sqwaking 7700 as soon as possible forces the system and the traffic will immediately show in orange on every sector at once, which can make us save precious seconds.
Turn
In normal situations, when we vector a traffic, we anticipate the new trajectory. As we don't know your intentions, when you turn, we've got the information about the new trajectory only 10-15 seconds (5000' ?) after the end of the turn (because of the caculations, averages, smoothenings included in the radar system). If you turn too often, "cleaning" your way in lower levels becomes much more difficult.
In this case, the biggest problem for us is to co-ordinate with lower sectors.
When one starts the descent, we get the information 4 seconds later. If we're not dealing with something else, we'll see it straight away. Expect then ONE message (that you won't hear) to confirm your clearance.
4 more seconds later, when we see that you've lost 1000', the emergency descent becomes obvious and we begin the co-ordinations with lower sectors.
Sqwak 7700
We've got automated systems to show a traffic performing an emergency descent to sectors who wouldn't see it in normal situation (filters to avoid overflow of useless informations), sqwaking 7700 as soon as possible forces the system and the traffic will immediately show in orange on every sector at once, which can make us save precious seconds.
Turn
In normal situations, when we vector a traffic, we anticipate the new trajectory. As we don't know your intentions, when you turn, we've got the information about the new trajectory only 10-15 seconds (5000' ?) after the end of the turn (because of the caculations, averages, smoothenings included in the radar system). If you turn too often, "cleaning" your way in lower levels becomes much more difficult.
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Automatic 7700 selection
Just curious.
Given the advancement of onboard FMS systems, would it not be possible to create a system whereby certain flight conditions would automatically cause the selection of 7700 on the transponder?
Understandably, the first task of the crew is to fly the aircraft, so if a way could be found to automatically alert ATC to an emergency descent which possibly also includes a turn off track - in a busy traffic environment, that cannot be a bad thing?
Given the advancement of onboard FMS systems, would it not be possible to create a system whereby certain flight conditions would automatically cause the selection of 7700 on the transponder?
Understandably, the first task of the crew is to fly the aircraft, so if a way could be found to automatically alert ATC to an emergency descent which possibly also includes a turn off track - in a busy traffic environment, that cannot be a bad thing?
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The issue about turning is long established and is only in part related to traffic avoidance.
If you want to descend in an expeditious manner do you;
a) shove the control column forward and change the loading by the maximum negative amount until the desired attitude is reached; or
b) roll the aircraft which will then all by itself lower the nose while maintaining 1g, trim as you go and smoothly level the wings in the new nose low attitude.?
Basic flying which is more gentle on the aircraft.
The argument about traffic below and going straight or turning has little relevance in domestic airspace since there is little point avoiding the parallel traffic simply to survive long enough to spear a crosser. Or cause a break-up by bunting the aircraft unnecessarily as per UK procedure.
With no pax on board and FL350 or less (depending on type) then as SNS3Guppy says once on oxygen and stable whats the point in rushing. There is as they quite also correctly point out 2 situations - with suspected structural damage and the alternative - system failure causing rapidly increasing cabin alt. Each requiring very different process.
With pax on board then pay heed to the fact that FL250 is the max for the rubber jungle being used for an entended period but - also no point in them being concious and breathing passing 10,000 if you have broken the aircraft entering the descent.
My opinion;
Crew Oxygen,
Internal communications,
Passenger Oxygen,
Descent - using the smallest change in g possible i.e. in most cases a gentle roll and allow the nose to drop. Situational awareness - Alps etc don't go for 10,000 in the alt sel. South China etc go for escape route.
7700 - it is in the checklist and as said above everyone in range gets an alarm and/or filter breakthrough.
Our job is to ensure the safety of our aircraft. I don't at that stage worry about anyone that is no on board our aircraft.
Mayday call when it is the next priority.
If you want to descend in an expeditious manner do you;
a) shove the control column forward and change the loading by the maximum negative amount until the desired attitude is reached; or
b) roll the aircraft which will then all by itself lower the nose while maintaining 1g, trim as you go and smoothly level the wings in the new nose low attitude.?
Basic flying which is more gentle on the aircraft.
The argument about traffic below and going straight or turning has little relevance in domestic airspace since there is little point avoiding the parallel traffic simply to survive long enough to spear a crosser. Or cause a break-up by bunting the aircraft unnecessarily as per UK procedure.
With no pax on board and FL350 or less (depending on type) then as SNS3Guppy says once on oxygen and stable whats the point in rushing. There is as they quite also correctly point out 2 situations - with suspected structural damage and the alternative - system failure causing rapidly increasing cabin alt. Each requiring very different process.
With pax on board then pay heed to the fact that FL250 is the max for the rubber jungle being used for an entended period but - also no point in them being concious and breathing passing 10,000 if you have broken the aircraft entering the descent.
My opinion;
Crew Oxygen,
Internal communications,
Passenger Oxygen,
Descent - using the smallest change in g possible i.e. in most cases a gentle roll and allow the nose to drop. Situational awareness - Alps etc don't go for 10,000 in the alt sel. South China etc go for escape route.
7700 - it is in the checklist and as said above everyone in range gets an alarm and/or filter breakthrough.
Our job is to ensure the safety of our aircraft. I don't at that stage worry about anyone that is no on board our aircraft.
Mayday call when it is the next priority.
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Our job is to ensure the safety of our aircraft. I don't at that stage worry about anyone that is no on board our aircraft.
Out of interest- what guidance do companies provide in the event that you get an RA whilst in the descent? It's no so far-fetched anymore.
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I would've thought that people not on board your aircraft may pose a grave threat to the safety of your aircraft- if they hit it at 900 knots.
If they don't get out of my way then I will have to do something so that I survive long enough to write the complaint.
Other aircraft have their own crews to look out for themselves. I am busy enough with my own at that stage.
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Ferris wrote :
I know TCAS and STCA don't work the same way, but I've got 2 questions :
- Would a RA trigger with this kind of a rate ?
- Would a RA be of any use anyway ?
STCA in my system would blink once here, once there, but the computer stops the alarm when it "thinks" it's already too late.
Hence the need for us to anticipate because the automated helps we benefit in normal conditions can be ineffective in such a case.
No STCA doesn't always mean there's no very short term conflict.
DFC,
That's the point !
If you want them to go out of your way, maybe a little help from ATC could help...
But as long as we don't know where you're going, we can't do much.
I perfectly understand your technical need for a turn. And I agree with you : straight ahead, right or left, there's a traffic.
If a turn lets you keep the remains of your plane around you, why not ?
Question : roughly, how many degrees do you need to drop the nose ?
Would this turn become SOP in every AO, then we would be able to anticipate only 2 possibilities : right or left turn. We would know how many degrees. Much easier than now, when anything can happen with no advice.
Stu_h's idea of an automated 7700 when the cabin climbs too fast seems great.
We immediately know you've got a problem, we know you're descending. And thanks to this new (hypothetical) worlwide SOP, we know you're turning X degrees.
After less than 8 seconds, we know if this is a right or a left turn.
Now that we know your intentsions, why not just fly the plane down to FL100, we take care of the surrounding traffic, military activities, et al... except maybe during the 10 first seconds.
See ? We've won almost 20 sec. And no need to talk.
Once the plane is fly-able again at FL100, contact us, say "MAYDAY", "diversion", "it's cold up here" or whatever you want.
We've got now plenty of time to navigate together (if you need help), file the papers (Mayday, new FPL to new destination, talk to supervisors, operations, the Pope...) and argue about descending without prior clearance.
Worlwide "SOP" has been implemented for TCAS-RA, why not for explosive decomp/emergency descent ?
in the event that you get an RA whilst in the descent?
- Would a RA trigger with this kind of a rate ?
- Would a RA be of any use anyway ?
STCA in my system would blink once here, once there, but the computer stops the alarm when it "thinks" it's already too late.
Hence the need for us to anticipate because the automated helps we benefit in normal conditions can be ineffective in such a case.
No STCA doesn't always mean there's no very short term conflict.
DFC,
If they don't get out of my way then I will have to do something so that I survive long enough to write the complaint.
If you want them to go out of your way, maybe a little help from ATC could help...
But as long as we don't know where you're going, we can't do much.
I perfectly understand your technical need for a turn. And I agree with you : straight ahead, right or left, there's a traffic.
If a turn lets you keep the remains of your plane around you, why not ?
Question : roughly, how many degrees do you need to drop the nose ?
Would this turn become SOP in every AO, then we would be able to anticipate only 2 possibilities : right or left turn. We would know how many degrees. Much easier than now, when anything can happen with no advice.
Stu_h's idea of an automated 7700 when the cabin climbs too fast seems great.
We immediately know you've got a problem, we know you're descending. And thanks to this new (hypothetical) worlwide SOP, we know you're turning X degrees.
After less than 8 seconds, we know if this is a right or a left turn.
Now that we know your intentsions, why not just fly the plane down to FL100, we take care of the surrounding traffic, military activities, et al... except maybe during the 10 first seconds.
See ? We've won almost 20 sec. And no need to talk.
Once the plane is fly-able again at FL100, contact us, say "MAYDAY", "diversion", "it's cold up here" or whatever you want.
We've got now plenty of time to navigate together (if you need help), file the papers (Mayday, new FPL to new destination, talk to supervisors, operations, the Pope...) and argue about descending without prior clearance.
Worlwide "SOP" has been implemented for TCAS-RA, why not for explosive decomp/emergency descent ?