Go Back  PPRuNe Forums > Flight Deck Forums > Tech Log
Reload this Page >

Emergency Descent - 36000'

Tech Log The very best in practical technical discussion on the web

Emergency Descent - 36000'

Old 2nd Jun 2013, 06:50
  #21 (permalink)  
Join Date: Jan 2004
Location: Here and there
Posts: 2,759
RAT 5, in part of your post you are suggesting that it's best to make a timely relaxed controlled descent with ATC in the loop but in the same breath you are suggesting that a TCAS RA would be a BAD thing.

Originally Posted by Rat 5
In the decompressurised environment, with all the noise and reduced visibility, lousy crew communications etc. do you really want a moment of "what shall we do/confusion" telling you to reduce or stop your descent? Personally I doubt it.
Lets consider why a TCAS RA is telling you to reduce your VS. Presumably it is so you don't collide with another aircraft yes? Surely a reduction in VS to comply with an RA is far better than having a midair. Now you might say "why not let the other aircraft take evasive action?" What if both aircraft need to take action? Maybe one aircraft doesn't have the ability to avoid the other all by itself. What if the other aircraft has a degraded TCAS system? Or maybe they're flying with an engine shutdown and have their TCAS to TA as well.
AerocatS2A is offline  
Old 2nd Jun 2013, 21:08
  #22 (permalink)  
Join Date: Jun 2003
Location: The Netherlands
Posts: 246
Emergency Descent - 36000'

In some companies they do not differentiate between rapid/explosive or subtle deco, only uncontrollable (or not), which leads to emo descent: PF: initiate descent; PM: simultaneously INFORM ATC, set TA only, squawk 7700.
JeroenC is offline  
Old 3rd Jun 2013, 20:45
  #23 (permalink)  
Join Date: Jun 2000
Location: last time I looked I was still here.
Posts: 4,510
As I understand it the Eurocontrol TCAS Review unit recommends that if you are flying a wounded bird, i.e. you have performance issues and do not want to receive an RA which requires an undesired manoeuvre, you should select TA Only. This will alert other a/c TCAS's that they will need to execute the avoiding RA. Seems quite simple and common sense to me. The only Boeing QRH that has this included is the Engine Failure/Loss of Thrust scenario. This is practised every 6 months in the sim and so everyone quotes it as the only occasion it is required. It might be their only experience of so doing. Ww do not always operate in a radar environment, remember.
Think about other scenarios where you do not want an RA requiring undesired manoeuvring. Jammed Flight controls: Stab trim problems requiring manual trim: Loss of HYD's = Manual reversion flight: Emergency Descent: Any flight control problem or thrust problem. There could be a whole host of them that should be at the crew's discretion. It is a tool to be used to help you survive the non-normal. If 2 a/c are conflicting I want to tell the other fella to get out of the way. How do I do that? TA Only. That's what it is for. It tells us that in the notes of the QRH SE case. Why does it not tell us that in other QRH's? Why are we not educated/encouraged to use airmanship and select it when needed to help us survive? Cast off the cloak of trained monkey and ask questions.
I quote the change in Boeing's advice on Stall recovery. Moons ago in basic training I was taught that a stall was an aerodynamic matter. it needed to be solved by aerodynamics. This includes basic physics. It was the same erect or inverted. Break the stall. Even an incipient stall it was the same basics. Boeings FCTM said Power & Reduce Attitude. I used to teach Reduce Attitude and increase Power that split second later. I did not know Boeing had changed the laws of aerodynamics. Reality stepped in and changed the philosophy. In other words questions were asked after an event (THY AMS) to see if improvements could be made, and they were. We are in an evolving environment where Mother Nature, Aerodynamics and Physics are always trying to tells us we shouldn't be there. We should not stop thinking and asking questions about how to improve our chances of the slaves defeating the lions. SOP's are not cast in stone; they should be an evolving living beast.
This is demonstrated by the many different ways airlines redefine the basic instruction manual of an a/c. They all do it differently yet all those different SOP's. They might all work, but they can't all be the best. They are adequate. I'm sure many have experienced every changing SOP's in an airline. Were they always for the better? How often have you changed companies, having flown with what you thought were excellent SOP's, only to learn new tricks and have the Ureka moment. I've done it a few times and in both directions: i.e. from crap to good and visa versa. Tit bits here and tit bits there. The brick walls I found trying to suggest improvements were as Jericho, but I didn't have any trumpets. We all survived, so that was the yard stick.
An open mind is a joy forever, but it brings some headaches from the blinkered.
I leave you to debate it out.
RAT 5 is offline  
Old 4th Jun 2013, 03:37
  #24 (permalink)  
Join Date: Mar 2002
Location: Seat 0A
Posts: 7,769
Very good, RAT 5.
Capn Bloggs is offline  
Old 4th Jun 2013, 03:56
  #25 (permalink)  
Join Date: Feb 2000
Location: CYZV
Age: 73
Posts: 1,259
I'm curious as to why the airplane bunted. Shirley on an emergency descent you first crank in bank to induce positive gee as well as turn off the airway for the descent, non?
pigboat is offline  
Old 4th Jun 2013, 04:33
  #26 (permalink)  
Join Date: Jan 2006
Location: In a far better place
Posts: 2,480
The primary purpose of notifying ATC of the impending emergency descent so they can clear the way for you and advise of the MORCA in the area and direction of the descent. I've had one in the good old 727 years ago. ATC provided me with a heading to avoid traffic and possible obstructions that would prevent descent to below 15,000'.

TXP to TA??? bonus points. However with the ambient noise, I doubt we would have heard any TA's let alone any RA's.
captjns is offline  
Old 4th Jun 2013, 05:05
  #27 (permalink)  
Join Date: Mar 2007
Location: Sandpit
Posts: 417
First get your O2 on ASAP…..then give yourself a few seconds to access the situation and get the pax O2 on too. There is no need to turn an emergency into a crisis by doing the wrong thing in a blind furry of selections. Once the O2 is on you have the best part of 22 mins (type specific) to get the aircraft down to below 10K. Once the O2 is on the absolute emergency is contained.

Aviate, Navigate, Communicate….that old bugbear.

I am often over very high terrain and limited in my decent due to the terrain and my escape routes at times can mean I would be pushing towards 22 mins before being able to get the aircraft to below 10k, so conversely in this instance where terrain is not limiting just because I can do an emergency decent to 10K why the absolute rush.

Im not saying chill out and have a coffee but more haste less speed……be expeditious not rushed.

Last edited by felixthecat; 4th Jun 2013 at 05:06.
felixthecat is offline  
Old 11th Jun 2013, 15:24
  #28 (permalink)  
Join Date: Dec 2006
Location: Florida and wherever my laptop is
Posts: 1,297
What everyone should realize is that ATC is not just one person. You may be flying along quite happily at FL410 in the high level sector, but below that may be multiple low level sectors - say FL280 - FL350 and FL180-FL270 and 6000ft - 1800ft - then there will be multiple sector boundaries that may not match the high level sector boundaries. So when your emergency hits you will talk to the current high level sector controller who is going to first deconflict you from aircraft below (you should of course have situational awareness on traffic immediately below and around you no? ) Then the controller will need to set up the transfer of your aircraft to the next control sector below his and possibly the one below that this takes a lot of talking especially if they have no hint that there is an emergency - they may not even rapidly answer his line.

This is because controllers may have filtered their displays so they don't see traffic outside the vertical boundaries of their sector. If you do NOT put 7700 on the controller in the sector below the one that you are in cannot see you unless the current controller 'points out' your flight in some way (often electronic) but he's also busy talking to aircraft that you may be about to hit.

It really makes total sense for the pilot not flying to select 7700 as soon as possible - then you don't have to tell ATC anything as that 77 breaks through all filtering and all sector controllers will immediately start clearing your path especially when they see your Mode C winding down. They also know not to start telling you about your uncleared level changes or turns as they realize that you are handling an emergency and that communicate comes last. Often controllers will start clearing other aircraft off the frequency to ensure that they can handle your problems.

The 7700 also flags in all supervisor positions including those in other centers and control facilities allowing the entire ATC provision to ramp up ready to assist in any way possible and other controllers will stop doing hand offs to the affected sector(s) etc etc. All that takes is selection of 7700 so don't hesitate to do it and don't hesitate to call MAYDAY (it does concentrate the controllers' minds) you can always downgrade the emergency to PAN once you are level at 10,000ft and handling seems OK etc.

Last edited by Ian W; 11th Jun 2013 at 15:27.
Ian W is offline  
Old 11th Jun 2013, 17:15
  #29 (permalink)  
Join Date: Jun 2000
Location: last time I looked I was still here.
Posts: 4,510
Guys: it seems there is some agreement to try and include ATC as a team player in this scenario. Sadly there has not been too many ATC opinions on this thread. More sadly, is every airline I've flown for, who ticks the boxes every 3 years in the sim with an Emergency Descent, is not receptive to ANY discussion about the real world in the execution of this critical manoeuvre. It is always, quite simply, an isolated blinkered hurtle down from whatever crz FL to 10,000' and sod everyone else. Tick in the box. I find this very unprofessional. Why can the XAA's and other relevant institutions not open their minds and review the dogma?
I doubt that every airline has the same SOP's; perhaps I'm wrong, but I would have though this should be a worldwide acceptable manoeuvre independent of type for the fundamentals: i.e. it should be an ICAO SOP worldwide. No doubt it will take a smoking hole to awaken other thoughts. Happened before.

Last edited by RAT 5; 11th Jun 2013 at 20:11.
RAT 5 is offline  
Old 11th Jun 2013, 17:17
  #30 (permalink)  
Join Date: Sep 2010
Location: England
Posts: 1,955
More than likely two holes.
Lord Spandex Masher is offline  
Old 12th Jun 2013, 07:36
  #31 (permalink)  
Join Date: Aug 2000
Posts: 1,324
The objective of an emergency descent is to bring the aircraft down to 10 000 ft as fast as possible.
Why? At 41000 ft you have some 10-15 seconds before you pass out. Then the clock is ticking towards brain damage.
Start the emergency descent while you declare and squawk emergency. Any advice after this point from ATC is very welcomed, but I will not start a debate with ATC before I start to go down. There is no time for that.
ManaAdaSystem is offline  
Old 12th Jun 2013, 08:25
  #32 (permalink)  
Join Date: Aug 2000
Posts: 1,324
Sorry, I'm not smart enough to understand what you are, or have been trying to say.
ManaAdaSystem is offline  
Old 15th Jun 2013, 05:25
  #33 (permalink)  
Join Date: Jan 2012
Location: Not far from the edge of the Milky Way Galaxy in the Orion Arm.
Posts: 510
I've always been intrigued about this "announcing" the emergency descent. What is the point,
well, there are people walking around the cabin, there are trollies in the aisles, there is hot coffee in the pots, there are children aboard the plane - there are old ladies tottering to the loo, how many other reasons do you want . . !?!? - there are quite a few freight jobs around
Natstrackalpha is offline  
Old 15th Jun 2013, 05:50
  #34 (permalink)  
Join Date: Mar 2002
Location: Seat 0A
Posts: 7,769
Originally Posted by NTA
... there are people walking around the cabin, there are trollies in the aisles, there is hot coffee in the pots, there are children aboard the plane - there are old ladies tottering to the loo, how many other reasons do you want . . !?!?
So what? What do you expect those you mentioned do? And do I then wait until they are all "organised" before I actually do anything? Judging by your concerns, and as I mentioned before, none of the pax have heard of the term "Emergency Descent"...it's certainly not mentioned in the pax brief...I would be better off announcing "stop what you're doing and hang on! Big rough dive coming shortly!".

Besides, as with a TCAS RA response, an Emergency Descent is a smooth, controlled manoeuvre that will not skittle anybody in the cabin, including trolleys. You freight dogs might chuck the aeroplane around, but I don't.
Capn Bloggs is offline  
Old 15th Jun 2013, 06:58
  #35 (permalink)  
Join Date: Sep 2003
Location: uk
Posts: 360
Straight copy from my company's QRH.

Emergency Descent <>

Condition: One or more of these occur: •Cabin pressure cannot be controlled when the airplane is above 14,000 feet •A rapid descent is needed.

1 Announce the emergency descent. PF will announce "CABIN CREW RAPID DESCENT, RAPID DESCENT" on the PA. The PM will set 7700 on the transponder, advise ATC and obtain the area altimeter setting.

2 Passenger signs . . . . . . . . . . . . . . . . . . . . . . ON

3 Without delay, descend to the lowest safe altitude, or 10,000 feet, whichever is higher.

4 ENGINE START switches (both) . . . . . . . . . CONT

5 Thrust levers (both) . . . . . . . . . Reduce thrust to minimum or as needed for anti-ice

Autopilot and autothrottle should remain engaged.

6 Speedbrake . . . . . . . . . . . . . . . .FLIGHT DETENT

- - - - - - - - - - - - - - - - - - - - - - -
If structural integrity is in doubt, limit speed as much as possible and avoid high maneuvering loads.

7 Set target speed to Mmo/Vmo.

8 When approaching the level off altitude:

Smoothly lower the SPEED BRAKE lever to the DOWN detent and level off. Add thrust and stabilize on altitude and airspeed.

9 Crew oxygen regulators . . . . . . . . . . . . . Normal

Flight crew must use oxygen when cabin altitude is above 10,000 feet. To conserve oxygen, move the regulator to Normal.

10 ENGINE START switches (both) . . . . . .As needed

11 The new course of action is based on weather, oxygen, fuel remaining and available airports. Use of long range cruise may be needed.

■ ■ ■ ■

Interesting point from RAT5, the TCAS we have has above and below, while in the cruise it is set to below, give us the ability to see down 6500'ish,
Will be something I will put to the fleet office for their reason not to set TA only.
rjay259 is offline  
Old 15th Jun 2013, 07:48
  #36 (permalink)  
Join Date: Sep 1999
Location: Middle England
Posts: 607
While your at it, get them to change No 1. Should surely be O2 on!
763 jock is offline  
Old 15th Jun 2013, 08:00
  #37 (permalink)  
Join Date: Mar 2002
Location: Seat 0A
Posts: 7,769
While your at it, get them to change No 1. Should surely be O2 on!
That would already have been covered by the "Cabin Hi Altitude" procedure Memory item.
Capn Bloggs is offline  
Old 15th Jun 2013, 10:17
  #38 (permalink)  
Join Date: Sep 2003
Location: uk
Posts: 360
Yes this is just the emergency descent cx,
The cabin depressurisation cx is another one,
rjay259 is offline  
Old 15th Jun 2013, 10:50
  #39 (permalink)  
Join Date: Jan 1999
Location: north of barlu
Posts: 6,169
Emergency descent or not ?

A few years back when in the cruise at FL410 I had a left pack trip off, just as the power was coming back at top of descent & cleared down to FL330 the right pack tripped off.

Within seconds I got the left pack online, the first officer asked for decent to FL100, then I ran the drill for getting the right pack back on line the left pack tripped off line !

By now the FO had the aircraft in a rapid descent and I got the right pack on line and we continued down to FL100.

At no time did the cabin altitude exceed 8000 ft or the cabin rate of climb exceed 300 ft/ min.

Once the right pack had demonstrated that it was staying on line I had time to brief the cabin crew but the passengers were clueless as to the goings on and did not realise that we had in effect made an emergency descent from FL410 to FL100.

I did as the problem started say to the FO that if I loose control of the cabin PX it was to be masks on and full emergency decent drills and in my mind had set a cabin ROC of 800 ft/ min to trigger this action.

So from this I have concluded that passengers only plummet towards the ground if they know that they are in an emergency descent or the newspapers tell them so and the descent it's self alone is not enought to merit comment from passengers.

Lets not make a drama out of a non crisis.

Last edited by A and C; 15th Jun 2013 at 10:52.
A and C is offline  
Old 15th Jun 2013, 15:07
  #40 (permalink)  
Join Date: Jun 2000
Location: last time I looked I was still here.
Posts: 4,510
I'm still curious about the hurtle at max ROD to 10,000'. Many of you go ski-ing at 12,000' That's arduous exercise. The auto pax O2 comes on at 14,000', so it is thought they're not going to die between 10 & 14,000'. So why are we encouraged to max it down to 10,000? I repeat, in real life ear drums have been burst by just such action. A max descent to 14,000' can be argued for, but surely a more relaxed 1500fpm to 12,000' and then 1000fpm to 10,000' will be more than adequate. No-on is going to suffer O2 starvation in this manner, but it could well save severe health damage to anyone on board, and that includes the crew. A ruptured ear drum is an incapacitation due to excruciating pain. I
I suspect this has been a left over from unpressurised a/c days, who were restricted to 10,000 crz, and also the ROD capabilities of older a/c and their O2 systems. I wonder if there has ever been a re-think. Like many things in our environment it often takes 'an event' to bring change. I still question things in the QRH, and guess what, over the years much has changed in them. They are not tablets of stone.
RAT 5 is offline  

Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service

Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.