Fear of Flying

**flyboy** · 05-07-12, 23:03

Originally Posted by JolieGal

Anyhow, if anyone could answer the stalling on high altitude question, I would really appreciate it. Meanwhile, go ahead and tell all your horror flying story. I may just put you all on ignore list

at high altitude the margin of safe speed for an aircraft is narrow. this is because the air is thinner the higher the altitude is. aircraft generate lift from the relative motion of air over its wings so logically speaking, if there is little air rushing over the wings then there is little lift. therefore the plane is expected to fly faster to compensate for the loss in lift but there is also max. structural speed which the plane should not exceed at any time otherwise the consequence is disintegration into pieces.

in the case of AF accident, i think, its not just a case of some faulty pitot tubes data and wrong reaction of pilots. both these may ve some part to play but not the only ones to b blamed. anyways, its very very very rare accidents happen on cruise phase of flights. my educated guess would b almost 95% of aviation accidents occur on the critical phases of either take off or landing. so considering the safety of aviation, chances r one in gazzilion for AF type of accident. now i hope at least u can get some sleep while cruising lolz

**ricky_id** · 05-07-12, 23:41

Plus I think many of us here are familiar with the term "Six Sigma". The airline industry as a whole is running at seven, at least so I learned back when I was at uni in 2008, when one takes the number of accidents relative to the number of flights.

**747-8** · 06-07-12, 06:54

Originally Posted by JolieGal

From what I gather, the AF 447 was stalling at high altitude and the pilots did everything wrong to recover from stalling (nose up instead of nose down). It is indeed scary if the very people you trust your life with have no clue what they're doing.

It is indeed scary, when a passenger such as yourself know the basic stall recovery technique of an aircraft, yet three highly experience pilots were not able to carry it out. I know the issues regarding AF447 is a lot more complicated than that, given the complex nature of the design of the aircraft they were flying, which in my humble opinion added to the confusion. One of the pilots at the controls actually did initiate the correct recovery technique, but his 'control' of the aircraft was later relinquished by the pilot who was originally in control. I dare say, a much less complex aircraft design, (where dual controls means just that), may have resulted in a more successful outcome.

**Davita** · 06-07-12, 07:41

Richard Quest.......the mouthy yet interesting Brit from CNN was most succinct on TV last night.
He opined that given the malfunction of a pitot head icing up that caused some instruments to malfunction...it the crew had left the Auto-pilot ON (it appears it gets its speed information from a different source) nothing would have happened and the aircraft would continue the flight as per. This would have given the pilots plenty of time to calmly assess their problem and resolve a remedy.
This was standard procedure I'd been trained and passed on since the late fifties. The joke used to be....If you're not sure what to do....sit on your hands.
This training seemed sadly lacking in this accident.

**lantern** · 06-07-12, 14:30

Originally Posted by Davita

The joke used to be....If you're not sure what to do....sit on your hands.
This training seemed sadly lacking in this accident.

Also applied to the infamous accident involving the son of the Russian pilot who was at the controls of an Airbus. Apparently if they had done nothing the aircraft would have recovered on it's own.

**Davita** · 06-07-12, 15:55

And who recalls the Learjet back in 1999 carrying the famous golfer Payne Stewart.
All on board were dead caused by lack of oxygen and yet the aircraft, on autopilot, flew 1500miles (around 4 hours) before running out of fuel and crashing.

**Hombre de Maiz** · 07-07-12, 10:04

Originally Posted by flyboy

...but there is also max. structural speed which the plane should not exceed at any time otherwise the consequence is disintegration into pieces....

This is true, but isn't the velocity ceiling first determined by the fact that if you fly too fast for a particular air density/temperature, the airflow over the wings will become turbulent and the center of lift will shift backwards or forwards, thereby causing a loss of lift?

**redsnapr** · 07-07-12, 11:24

Precisely, Hombre. High speed stall is reached at a combination of higher altitudes and high weights, i.e. at a given weight if you keep climbing at a constant speed (lower than max. structural speed), you will reach an altitude where high speed stall will occur.

The problem of a coffin corner recovery is how to handle the airplane in a situation where the lower speed will cause a stall, and the higher speed will cause a high speed stall.

**redsnapr** · 07-07-12, 11:49

Someone wishing to go deeply into technical stuff (and to show joliegal how seriously aviation safety is taken by regulatory agencies, manufacturers amnd operators) may want to read this. Be forewarned: this stuff is really dry...