Other aviation hazards
Thread Starter
Other aviation hazards
In recent incidents in aerial public transport ops (including the JAL landing collision and B737 door blowout) some commentators have noted that regulatory authorities are slow to respond unless large loss of life is involved. Here are some other current aviation hazards that (thus far) have not caused severe accidents but have the potential to do so:
Low and variable transition altitudes in non-US states. Mis-set altimeters can lead to level busts or terrain warnings. In the UK the CAA issue notams about altimeter settings whenever a low pressure weather system occurs. A world-wide TA of (say) 20,000 ft (or 6000m in metric areas) would allow altimeter resetting during climb and descent to be done during low workload flight phases.
Currently rapid depressurisation checklists mandate immediate initiation of descent without regard to ATC requirements. These checklists originated many years ago when high altitude air traffic density was much lower. An airliner plummeting through busy airspace these days might trigger multiple conflicting nearby TCAS RAs or, in the worst case scenario, collide with traffic below. The mantra 'aviate, navigate, communicate' is clearly not relevant in this situation.
Climate change is generating stronger surface winds which in turn will increase the incidence of landings with severe crosswinds. YouTube videos seem to suggest that landing with crab is now acceptable, but a mishandled landing might lead to gear collapse or airframe/engine ground strikes. Perhaps crosswind landing technique should be debated and standard procedures established, perhaps specific for different aircraft types.
Overhead luggage compartments in airliner cabins should be locked for take-off and landing to prevent delays to evacuations.
Low and variable transition altitudes in non-US states. Mis-set altimeters can lead to level busts or terrain warnings. In the UK the CAA issue notams about altimeter settings whenever a low pressure weather system occurs. A world-wide TA of (say) 20,000 ft (or 6000m in metric areas) would allow altimeter resetting during climb and descent to be done during low workload flight phases.
Currently rapid depressurisation checklists mandate immediate initiation of descent without regard to ATC requirements. These checklists originated many years ago when high altitude air traffic density was much lower. An airliner plummeting through busy airspace these days might trigger multiple conflicting nearby TCAS RAs or, in the worst case scenario, collide with traffic below. The mantra 'aviate, navigate, communicate' is clearly not relevant in this situation.
Climate change is generating stronger surface winds which in turn will increase the incidence of landings with severe crosswinds. YouTube videos seem to suggest that landing with crab is now acceptable, but a mishandled landing might lead to gear collapse or airframe/engine ground strikes. Perhaps crosswind landing technique should be debated and standard procedures established, perhaps specific for different aircraft types.
Overhead luggage compartments in airliner cabins should be locked for take-off and landing to prevent delays to evacuations.
My personal biggest concern is incorrect data entry/incorrect intersection departures leading to crews trying to get airborne with insufficient flap/thrust. There have been a few incidents already where only the grace of god has prevented a hull loss.
Currently rapid depressurisation checklists mandate immediate initiation of descent without regard to ATC requirements. These checklists originated many years ago when high altitude air traffic density was much lower. An airliner plummeting through busy airspace these days might trigger multiple conflicting nearby TCAS RAs or, in the worst case scenario, collide with traffic below. The mantra 'aviate, navigate, communicate' is clearly not relevant in this situation.
I will accept that the accuracy of GNSS navigation increases the risk posed to emergency descent scenarios by aircraft being precisely on published tracks, rather than scattered either side of them as in days gone by, but TCAS more than compensates for that IMHO. The best way to reduce that risk is to reduce the use of published tracks, and indeed we are seeing growth of free route airspace in the upper air.
Late edit: I should also have mentioned decompression sickness, for which there is no defence other than immediate descent if severe injury, disability or potential death is to be averted. Think of its effect on the body as similar to the effect of opening the cap on a bottle of carbonated drink... except those bubbles are potentially fatal, so you don't spend time planning how best to screw the cap back on, you get the hell on with it. There's no hope of finding a hyperbaric facility capable of treating hundreds of pax simultaneously....
Last edited by Easy Street; 7th Jan 2024 at 09:44.
My immediate action after doing the decompression drill would be to get off the airway (turn left or right 90 degrees initially) during the initial descent, in order to avoid other traffic on the airway.
In the UK you DONT do this due to the density of Airways. Stay on track so ATC can move people away from YOU.
suggest that landing with crab is now acceptable
Ex 737-400 and 747-400 pilot here. Wings level at touchdown or pod strike! Training all focussed avoiding wing down even to the extent of having the cockpit close to the upwind edge of the runway with max crosswind in the ‘47…
Thread Starter
Are you proposing here that aircraft should remain at their cleared level while depressurised and communicate with ATC before initiating emergency descent, working from the idea that emergency oxygen will supposedly last 15 minutes or so? If so, have you considered that time of useful consciousness is measured in single-digit seconds at modern airliner cruise altitudes? It is doubtful IMHO that all passengers and cabin crew would succeed in donning masks, much less be able to report 100% success to the flight deck in any kind of meaningful timeframe, so the only course open to pilots wishing to maximise the chances of survival of anyone who's failed to don a mask is to descend immediately upon depressurisation. A depressurised cockpit is not a place for complex thinking, cross-monitoring, assessing the state of the cabin, or negotiating a descent clearance with ATC - all communication is difficult under emergency oxygen, and anyone who has undergone decompression training can attest to the shock inducing effect of sudden cold and hyperventilation, which is likely to persist until some time after emergency oxygen is established. What's needed in this situation is a simple, mechanical drill which addresses the immediate and otherwise-inescapable threat to life presented by high cabin altitude. By comparison, midair collision is only a possibility, and one which other parties (not suffering the immediate and certain threat of decompression) can do their part to avert with full mental capacity in relative warmth and comfort. The existence of TCAS surely makes this a much safer procedure than it was many years ago. Triggering multiple RAs should be the least of anyone's concerns in this situation because TCAS is very good at changing its instructions as required to deal with the highest threat, whether that is the descending emergency aircraft or another aircraft making an RA against it.
Perhaps positive pressure oxygen systems for passengers and cabin crew would help to mitigate hypoxia effects while the flight deck crew attempt to negotiate an emergency descent clearance with ATC.
Hopefully this headline will never appear in our newspapers:
.
COLLISION AIRLINER DESCENDED WITHOUT PERMISSION AFTER CABIN AIR PRESSURE FAILURE
The hypoxia and other distressing effects you describe would clearly be less injurious to the overall physical wellbeing of passengers and crew than mid-air collision.
Perhaps positive pressure oxygen systems for passengers and cabin crew would help to mitigate hypoxia effects while the flight deck crew attempt to negotiate an emergency descent clearance with ATC.
Hopefully this headline will never appear in our newspapers:
.
Perhaps positive pressure oxygen systems for passengers and cabin crew would help to mitigate hypoxia effects while the flight deck crew attempt to negotiate an emergency descent clearance with ATC.
Hopefully this headline will never appear in our newspapers:
.
COLLISION AIRLINER DESCENDED WITHOUT PERMISSION AFTER CABIN AIR PRESSURE FAILURE
From an ex- ATCO... Emergency squawk will get ATC's instant attention, and not just the unit you're talking to. (or not, if you're sorting out the aeroplane.) If they see you start a descent they'll clear traffic below out of the way - if you have time to get a Mayday out then great, but I can't believe you would expect a crew to sit there drumming their fingers waiting to call ATC while someone else is transmitting...
I'd suggest that a prime hazard is the sort of gash N American RT demonstrated by the Alaskan pilot during this event. Sloppy, indistinct, non-standard and non-specific rambling instead of a Professinal MAYDAY call - a word they never uttered.
Leave alone asking - yes! asking! for descent in a rapid depressurisation whilst evidently not wearing an oxygen mask - completely contrary to the memory drill...
Leave alone asking - yes! asking! for descent in a rapid depressurisation whilst evidently not wearing an oxygen mask - completely contrary to the memory drill...
Last edited by meleagertoo; 7th Jan 2024 at 12:27.
Nothing to do with being American. I know of an incident in Australia where the crew didn't declare a Mayday with a depressurization. Part of the issue is the dominance of media in its various forms and it's focus on sensationalism. There has been plenty of that lately. IMHO crews from around the world don't want to draw attention to their situation even if it is depress. Don't forget the crew in the 737 weren't faced with the scenario that endless sim sessions train for and that is the failure at FL370. I would imagine that this crew were dealing with a fair amount of startle factor trying to understand why they were depressurizing climbing through 16000'. Which crew anywhere in the world would anticipate a part of the airframe detaching on a brand new aircraft?
The offset works well on the B747/744, B757, B767, it doesn't behave quite so on the B777. If the drift is eased off by rudder with an offset on the B777, the aircraft ends up offset from the CL. It is one of two weirdnesses of the 777. The other one being that most aircraft will swing towards the wind direction on a takeoff, the B777 doesn't that initially, it actually has an out of wind tendency, that occurs until passing about 80-90 kts. These were so striking I went through the QAR data of aircraft to verify the perceived response.
Thread Starter
From 'How To Do Well In The Sim':
This is a personal opinion - and probably a minority one, judging by other posters' comments. I never experienced a real rapid depress and therefore never felt the physical distresses described above.
This is a personal opinion - and probably a minority one, judging by other posters' comments. I never experienced a real rapid depress and therefore never felt the physical distresses described above.
Pegase Driver
Join Date: May 1997
Location: Europe
Age: 74
Posts: 3,692
Likes: 0
Received 0 Likes
on
0 Posts
Emergency descent ? Aviate first communicate next ..Do not ask permission , That what we are told to expect as en-route controllers. .Turing 15 Degrees off track is what is recommended in Oceanic airspace I believe ( it was in my days , correct me if I am wrong) but in dense Condimental airspace , makes no difference where you go laterally as there is likely going to be someone in your way , so squawking A7700 is the only sensible way to attract attention to the ATC sectors below you and like this everybody will try to keep others clear. Remember the R/T frequency you are in is possibly only a few thousand feet deep, In an emergency descent from say 38.000 ft to 10.000 above say Belgium you could cross no less that 6 different sectors , from 2 different ATC centers ..and possibly a TMA as well so the approach sector of an airport , and it could be a military one. , So "a mayday " will help only the first sector .
Squawking 7700 and just saying on the R/T : your calf sign + emergency descent to 10.000 ft is what I will do . In very busy airspace . or in shared CIV/MIL airspace , like China for instance,. switching to 121.5 is not a bad idea either as the military are likely to be tuned in and keep their aircraft out of the way.
. And to make things more complicated , as was said before, TCAS will not help much at these kind of rates of descent ..
Squawking 7700 and just saying on the R/T : your calf sign + emergency descent to 10.000 ft is what I will do . In very busy airspace . or in shared CIV/MIL airspace , like China for instance,. switching to 121.5 is not a bad idea either as the military are likely to be tuned in and keep their aircraft out of the way.
. And to make things more complicated , as was said before, TCAS will not help much at these kind of rates of descent ..
Join Date: Nov 2004
Location: Here, there, and everywhere
Posts: 1,124
Likes: 0
Received 12 Likes
on
7 Posts
The offset works well on the B747/744, B757, B767, it doesn't behave quite so on the B777. If the drift is eased off by rudder with an offset on the B777, the aircraft ends up offset from the CL. It is one of two weirdnesses of the 777. The other one being that most aircraft will swing towards the wind direction on a takeoff, the B777 doesn't that initially, it actually has an out of wind tendency, that occurs until passing about 80-90 kts. These were so striking I went through the QAR data of aircraft to verify the perceived response.
According to Boeing, the swinging toward the wind at lower speeds is called the Anti-Weathervaning effect and affects all Boeing twin jets. But I suspect that the bigger the engines, the more the effect as the crosswind acts on the nacelles(rotating the aircraft in one direction) versus the effect on the vertical tail(rotating the aircraft in the other direction).
“Climate change is generating stronger surface winds which in turn will increase the incidence of landings with severe crosswinds. “
Really? Talk about drinking the Kool-Aid and blaming everything on a phenomenon that is in dispute.
Really? Talk about drinking the Kool-Aid and blaming everything on a phenomenon that is in dispute.
I'd suggest that a prime hazard is the sort of gash N American RT demonstrated by the Alaskan pilot during this event. Sloppy, indistinct, non-standard and non-specific rambling instead of a Professinal MAYDAY call - a word they never uttered.
Leave alone asking - yes! asking! for descent in a rapid depressurisation whilst evidently not wearing an oxygen mask - completely contrary to the memory drill...
Leave alone asking - yes! asking! for descent in a rapid depressurisation whilst evidently not wearing an oxygen mask - completely contrary to the memory drill...
The topic of “Mayday” vs “Emergency” comes up often on PPRune. I’ve been flying Jets since 1986 in the USAF and Commercially. All I can tell you is, in the U.S., we declare an “EMERGENCY” this phraseology has been hammered into US pilots since day one of PPL training. I would only say “MAYDAY” if I were flying outside of U.S. airspace, which I did regularly for 28 years. I’m not arguing with you as to which is correct, I agree there should be one standard phrase to convey a serious Emergency, and I understand everyone else uses the MAYDAY terminology except for the U.S. It’s just never been an emphasis item in any training program or directive. The use of “MAYDAY” was required by the USAF overseas, but never in U.S. Airspace. I don’t know why. Don’t get your “panties in a bunch” over the RT in this incident, believe me, when any pilot declares an “EMERGENCY” in the U.S. it will illicit the exact same response as declaring “MAYDAY”. Hopefully emphasis will be placed on ONE STANDARD Phrase in the future.
Videos and photos of landing aircraft with large crab angles are very misleading. A zoom lense will foreshorten dimensions in the fore/aft direction of the lense. The effect is to make any crab angle appear much larger than reality.