Centaurus
27th Sep 2018, 15:12
This thread is allied to the ATSB report on the King Air accident at Essendon. Mods may decide to move it to that thread or leave it here as a separate discussion.
The ATSB report states in part: There was insufficient evidence to determine why the pilot delayed rotation from 94 kt to 111 kt or why the take-off was not rejected.
Essendon Runway 17 had a potentially deadly overrun into the Tullamarine Freeway if the aircraft is not stopped by the end of the existing overrun area. This writer has previously advocated Essendon airport authorities seriously consider additional aircraft stopping measures in the form crushed material beyond the runway end particularly where an over-run could lead to fatal consequences to aircraft occupants and those caught in the way. See:https://en.wikipedia.org/wiki/Engineered_materials_arrestor_system No interest was shown by the relevant authority.
The take off roll of the KingAir was longer than normally expected and the delayed rotation proved this. Some sources questioned why the pilot did not abort the take of roll once it became clear that he was having problems with directional control approaching 94 knots the nominal rotation speed. Unless there is a definite indication of a serious problem during the takeoff roll such as fire warning, a more subtle indication such as the aircraft pulling slightly to one side may be interpreted by the pilot as something vaguely amiss but he doesn't have sufficient marked cues to make the critical decision to abandon the take off roll. Two examples using real incidents may illustrate this.
Firstly: https://www.fss.aero/accident-reports/dvdfiles/US/1989-09-20-US.pdf
A Boeing 737-400 started its take off roll with the F/O as PF. The crew were unaware that an electrical fault had moved its rudder trim from neutral to full scale left. The rudder trim had been confirmed at neutral before engine start. It takes 29 seconds for the rudder trim to move from neutral to full scale in one direction. The only clue would be a slightly offset rudder pedal position which could easily go unnoticed. During the early part of the take off run the aircraft started to drift left of the runway centreline; enough to concern the PF which he voiced to the captain. With the aircraft accelerating, a short discussion took place between the two pilots culminating in the captain taking over full control. He was able to track back towards the centreline and made the decision to abort but did not commence the abort procedure including reverse thrust and braking, until on the centreline. Earlier in the beginning of the take off roll there was a delay before full power was selected due to a problem with the autothrottle selection. That delay used up more runway. The result was the aircraft overran the far end and went into a river causing fatalities.
In short, the combinations of uncertainty caused initially by the aircraft gradually veering to the left and getting worse as speed picked up, followed by a delay before the captain took control and then his slow actions with regard to stopping the aircraft, all led to the fatal overrun. But it all started with a feeling that something was not quite right early in the take off roll. The King Air pilot at Essendon no doubt had a similar feeling that something was not quite right; but by the time things were getting serious in terms of directional control and VR approaching, the presence of the Tullamarine Freeway right off the end of the runway may have influenced his decision to keep flying rather than risk a high speed abort.
Example No. 2
The feeling that something wasn't quite right was evident in this case during a midnight take off in a 737-200 from the 5600 feet length runway on Nauru island in the Central Pacific Region.. There was no overrun area for Runway 30. There was however, a road five metres away and a cliff covered with boulders and then the ocean. Readers may be familiar from Air Disaster TV videos, of the Air Florida 737 crash into Washington's Potomac River. See: https://en.wikipedia.org/wiki/Air_Florida_Flight_90 (https://en.wikipedia.org/wiki/Air_Florida_Flight_90)
On that occasion ice had blocked the sensors to engines power indicating instruments (EPR) resulting in the crew thinking they had full power when the actual power was much less than planned. The aircraft used the full length of runway and hit a bridge shortly after lift off and crashed into the river.
In the case of the 737 incident at Nauru, it wasn't ice that blocked the sensors and thus gave erroneous high power engine instrument indications, but instead a combination of phosphate dust from nearby mines and insects that had blocked the thrust sensors. The result was the same in that the 737 used all the runway because of lower power than expected. Because it was a night takeoff and therefore a more difficult perception of distance remaining, it wasn't until the last 200 metres of runway and airspeed well below V1, that it suddenly became evident the aircraft would not get airborne before the end of the runway. The captain's decisive actions to manually apply full available throttles to the stops and carefully rotate at the extreme end, saved the day (or night in this case). The jet exhaust blast lifted parts of the adjacent road back on to the runway. It was the closest shave of this writers career. I know this because I was in the jump seat praying the captain would not abort and finish over the cliff and into the sea. There was lots of sharks in the area.
In each of the examples given, there was a vague feeling on the flight deck that something wasn't quite right early in the takeoff roll but not enough evidence that an abort was warranted. All the engine instruments looked normal in that needles were all parallel and in expected positions. But in the early part of the take off roll a keen eye would have picked a slight discrepancy between expected EPR (engine pressure ratio) and actual engine N1 or RPM indications. In the case of the Nauru incident, all three of us in the cockpit missed the warning signs. But that is being wise after the event.
Referring back to the King Air Essendon accident. One can now perhaps understand the human factors aspect of the pilot's decision to keep on going when he probably only had a vague idea that something wasn't quite right early during his takeoff roll but couldn't pin it down until too late to abort knowing there was a potentially fatal overrun on to the Tullamarine freeway below.
The ATSB report states in part: There was insufficient evidence to determine why the pilot delayed rotation from 94 kt to 111 kt or why the take-off was not rejected.
Essendon Runway 17 had a potentially deadly overrun into the Tullamarine Freeway if the aircraft is not stopped by the end of the existing overrun area. This writer has previously advocated Essendon airport authorities seriously consider additional aircraft stopping measures in the form crushed material beyond the runway end particularly where an over-run could lead to fatal consequences to aircraft occupants and those caught in the way. See:https://en.wikipedia.org/wiki/Engineered_materials_arrestor_system No interest was shown by the relevant authority.
The take off roll of the KingAir was longer than normally expected and the delayed rotation proved this. Some sources questioned why the pilot did not abort the take of roll once it became clear that he was having problems with directional control approaching 94 knots the nominal rotation speed. Unless there is a definite indication of a serious problem during the takeoff roll such as fire warning, a more subtle indication such as the aircraft pulling slightly to one side may be interpreted by the pilot as something vaguely amiss but he doesn't have sufficient marked cues to make the critical decision to abandon the take off roll. Two examples using real incidents may illustrate this.
Firstly: https://www.fss.aero/accident-reports/dvdfiles/US/1989-09-20-US.pdf
A Boeing 737-400 started its take off roll with the F/O as PF. The crew were unaware that an electrical fault had moved its rudder trim from neutral to full scale left. The rudder trim had been confirmed at neutral before engine start. It takes 29 seconds for the rudder trim to move from neutral to full scale in one direction. The only clue would be a slightly offset rudder pedal position which could easily go unnoticed. During the early part of the take off run the aircraft started to drift left of the runway centreline; enough to concern the PF which he voiced to the captain. With the aircraft accelerating, a short discussion took place between the two pilots culminating in the captain taking over full control. He was able to track back towards the centreline and made the decision to abort but did not commence the abort procedure including reverse thrust and braking, until on the centreline. Earlier in the beginning of the take off roll there was a delay before full power was selected due to a problem with the autothrottle selection. That delay used up more runway. The result was the aircraft overran the far end and went into a river causing fatalities.
In short, the combinations of uncertainty caused initially by the aircraft gradually veering to the left and getting worse as speed picked up, followed by a delay before the captain took control and then his slow actions with regard to stopping the aircraft, all led to the fatal overrun. But it all started with a feeling that something was not quite right early in the take off roll. The King Air pilot at Essendon no doubt had a similar feeling that something was not quite right; but by the time things were getting serious in terms of directional control and VR approaching, the presence of the Tullamarine Freeway right off the end of the runway may have influenced his decision to keep flying rather than risk a high speed abort.
Example No. 2
The feeling that something wasn't quite right was evident in this case during a midnight take off in a 737-200 from the 5600 feet length runway on Nauru island in the Central Pacific Region.. There was no overrun area for Runway 30. There was however, a road five metres away and a cliff covered with boulders and then the ocean. Readers may be familiar from Air Disaster TV videos, of the Air Florida 737 crash into Washington's Potomac River. See: https://en.wikipedia.org/wiki/Air_Florida_Flight_90 (https://en.wikipedia.org/wiki/Air_Florida_Flight_90)
On that occasion ice had blocked the sensors to engines power indicating instruments (EPR) resulting in the crew thinking they had full power when the actual power was much less than planned. The aircraft used the full length of runway and hit a bridge shortly after lift off and crashed into the river.
In the case of the 737 incident at Nauru, it wasn't ice that blocked the sensors and thus gave erroneous high power engine instrument indications, but instead a combination of phosphate dust from nearby mines and insects that had blocked the thrust sensors. The result was the same in that the 737 used all the runway because of lower power than expected. Because it was a night takeoff and therefore a more difficult perception of distance remaining, it wasn't until the last 200 metres of runway and airspeed well below V1, that it suddenly became evident the aircraft would not get airborne before the end of the runway. The captain's decisive actions to manually apply full available throttles to the stops and carefully rotate at the extreme end, saved the day (or night in this case). The jet exhaust blast lifted parts of the adjacent road back on to the runway. It was the closest shave of this writers career. I know this because I was in the jump seat praying the captain would not abort and finish over the cliff and into the sea. There was lots of sharks in the area.
In each of the examples given, there was a vague feeling on the flight deck that something wasn't quite right early in the takeoff roll but not enough evidence that an abort was warranted. All the engine instruments looked normal in that needles were all parallel and in expected positions. But in the early part of the take off roll a keen eye would have picked a slight discrepancy between expected EPR (engine pressure ratio) and actual engine N1 or RPM indications. In the case of the Nauru incident, all three of us in the cockpit missed the warning signs. But that is being wise after the event.
Referring back to the King Air Essendon accident. One can now perhaps understand the human factors aspect of the pilot's decision to keep on going when he probably only had a vague idea that something wasn't quite right early during his takeoff roll but couldn't pin it down until too late to abort knowing there was a potentially fatal overrun on to the Tullamarine freeway below.