New York Plane Crash
Discussion
ks anyway...
No it's not.
Apparently, Continental Airlines has an internal policy of flying manually in icy conditions. This aircraft was not owned or crewed by Continental Airlines, it was a franchise operator for Continental called Colgan Airways - which may have very different rules.
Apparently, Continental Airlines has an internal policy of flying manually in icy conditions. This aircraft was not owned or crewed by Continental Airlines, it was a franchise operator for Continental called Colgan Airways - which may have very different rules.
Edited by Eric Mc on Sunday 15th February 19:30
It might depend on the types of airports different airlines use. A small carrier like Colgan might operate in and out of smaller, tighter airports which have more difficult and steeper approaches and might feel that the safest option is to allow the aircraft to set itself up using the airport's landing aids.
One of the problems with autopilot systems is that they tend to try to keep flying the plane until the moment they no longer can cope. If there was ice building up on the wings, the autopilot would have been struggling to keep the aircraft in trim but would have done a great job right until the point it gave up. At this stage, it would disengage and hand manual control back to the crew. If this was at a critical point just before landing, the crew would have had little time to ascertain what was going on and the plane may have instantly stalled.
One of the problems with autopilot systems is that they tend to try to keep flying the plane until the moment they no longer can cope. If there was ice building up on the wings, the autopilot would have been struggling to keep the aircraft in trim but would have done a great job right until the point it gave up. At this stage, it would disengage and hand manual control back to the crew. If this was at a critical point just before landing, the crew would have had little time to ascertain what was going on and the plane may have instantly stalled.
Eric Mc said:
It might depend on the types of airports different airlines use. A small carrier like Colgan might operate in and out of smaller, tighter airports which have more difficult and steeper approaches and might feel that the safest option is to allow the aircraft to set itself up using the airport's landing aids.
One of the problems with autopilot systems is that they tend to try to keep flying the plane until the moment they no longer can cope. If there was ice building up on the wings, the autopilot would have been struggling to keep the aircraft in trim but would have done a great job right until the point it gave up. At this stage, it would disengage and hand manual control back to the crew. If this was at a critical point just before landing, the crew would have had little time to ascertain what was going on and the plane may have instantly stalled.
Should they not be building a greater margin of error into these systems? If the autopilot is working at say 99%, could they have it pass that infomation on before disengaging completely?One of the problems with autopilot systems is that they tend to try to keep flying the plane until the moment they no longer can cope. If there was ice building up on the wings, the autopilot would have been struggling to keep the aircraft in trim but would have done a great job right until the point it gave up. At this stage, it would disengage and hand manual control back to the crew. If this was at a critical point just before landing, the crew would have had little time to ascertain what was going on and the plane may have instantly stalled.
This accident may sadly be a classic case of icing-induced tailplane stall 
The ATR and DHC6/7/8 are all pretty susceptible to it unfortunately. If the crew were flying the approach with the autopilot in then they would not have had time to recognise the warning signs.
Fortunately airframe icing is very rare on swept wing jet aircraft so it's not an issue I have to worry about that often, if ever. (Only ever had to use the wing anti-ice system in anger on maybe 3 occasions in the past decade)
There is an excellent NASA information/training film Here - it's fairly long (20ish mins) but explains the issue well.
The ATR and DHC6/7/8 are all pretty susceptible to it unfortunately. If the crew were flying the approach with the autopilot in then they would not have had time to recognise the warning signs.
Fortunately airframe icing is very rare on swept wing jet aircraft so it's not an issue I have to worry about that often, if ever. (Only ever had to use the wing anti-ice system in anger on maybe 3 occasions in the past decade)
There is an excellent NASA information/training film Here - it's fairly long (20ish mins) but explains the issue well.
Although not exactly the same, this crash seems to share a lot of similarities with the crash of the American Airlines ATR-42 in Indiana. On that occasion, it was icing up of the ailerons that caused the problem.
From what the initial investigation results do seem to be saying is that the problem with the Dash 8 was indeed with the tailplane/elevators. The aircraft appears to have impacted in a flat but nose high atitude with little forward speed - the classic indication of a stalled tailplane and ineffectual elevators. Again, this shows simularities with the 1972 Trident crash at Staines which, although not caused by icing, suffered what was called a Deep Stall in which the tailplane/elevators were rendered ineffective and the aircraft could not be recovered from its stalled position.
Both the Trident and the Dash 8 had/have T-Tails which are more prone to this type of situation.
From what the initial investigation results do seem to be saying is that the problem with the Dash 8 was indeed with the tailplane/elevators. The aircraft appears to have impacted in a flat but nose high atitude with little forward speed - the classic indication of a stalled tailplane and ineffectual elevators. Again, this shows simularities with the 1972 Trident crash at Staines which, although not caused by icing, suffered what was called a Deep Stall in which the tailplane/elevators were rendered ineffective and the aircraft could not be recovered from its stalled position.
Both the Trident and the Dash 8 had/have T-Tails which are more prone to this type of situation.
Knowing how much ice is building up on your control surfaces is difficult to ascertain. If you are using autopilot, the degradation of the effectiveness of the controls is masked by the fact that the autopilot will keeep flying the aircraft right up to the moment it can't do this anymore. At this point it will probably disengage, effectively handing a virtually unflyable aeroplane back to the crew. That was certainly a major factor in the Indiana ATR-42 crash.
The problem for the crew is knowing at what point to switch from autopilot control to manual control. They will be very much dependent on weather information given to them by ground controllers as to whether icing conditions are likely. Airframe icing is not just a function of cold weather. It is a function of atmopspheric conditions and altitude as well. You can get airframe icing on a warm sunny day. Conversly, you may not experience airframe icing on a bitterly cold winter's day.
The problem for the crew is knowing at what point to switch from autopilot control to manual control. They will be very much dependent on weather information given to them by ground controllers as to whether icing conditions are likely. Airframe icing is not just a function of cold weather. It is a function of atmopspheric conditions and altitude as well. You can get airframe icing on a warm sunny day. Conversly, you may not experience airframe icing on a bitterly cold winter's day.
Eric Mc said:
Knowing how much ice is building up on your control surfaces is difficult to ascertain. If you are using autopilot, the degradation of the effectiveness of the controls is masked by the fact that the autopilot will keeep flying the aircraft right up to the moment it can't do this anymore. At this point it will probably disengage, effectively handing a virtually unflyable aeroplane back to the crew. That was certainly a major factor in the Indiana ATR-42 crash.
The problem for the crew is knowing at what point to switch from autopilot control to manual control. They will be very much dependent on weather information given to them by ground controllers as to whether icing conditions are likely. Airframe icing is not just a function of cold weather. It is a function of atmopspheric conditions and altitude as well. You can get airframe icing on a warm sunny day. Conversly, you may not experience airframe icing on a bitterly cold winter's day.
Totally agree. The problem for the crew is knowing at what point to switch from autopilot control to manual control. They will be very much dependent on weather information given to them by ground controllers as to whether icing conditions are likely. Airframe icing is not just a function of cold weather. It is a function of atmopspheric conditions and altitude as well. You can get airframe icing on a warm sunny day. Conversly, you may not experience airframe icing on a bitterly cold winter's day.
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