Norwegian B737-800 almost stalls at EFKT?
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Norwegian B737-800 almost stalls at EFKT?
Finnish aviation news site lentoposti.fi has posted a news item on a near stalling incident at Kittilä (EFKT), in Northern Finland:
Suomen onnettomuustutkijat avustamaan norjalaisia Kittilässä tapahtuneen vaaratilanteen tutkinnassa | lentoposti.fi
Short summary in English:
The B737 registration LN-BYM (NAX5630) was flying the ILS 34 approach to Kittilä (EFKT), in Northern Finland, when at 3250 ft on the glideslope with autopilot engaged and flaps partially extended the aircraft started a sudden climb with full thrust, at the same time letting the airspeed decrease near stalling speed. The aircraft climbed 1500 ft during the incident before the pilots regained control.
The next approach was successful and no technical faults have been found so far in the aircraft.
Norway's Accident Investigation board (SHT) is investigating this incident together with it's Finnish counterpart, NTSB and Boeing. SHT has the FDR and some aircraft parts in its possession.
Some facts which may be irrelevant in this case: EFKT34 ILS G/S is 3.4 degrees steep, with typically tailwind conditions (no precision approach to 16 available), 2.5 km runway and often slippery runway conditions. Depending on time and day the airport may be manned either with an ATCO (TWR) or an AFIS person.
Any ideas from B737 pilots?
Suomen onnettomuustutkijat avustamaan norjalaisia Kittilässä tapahtuneen vaaratilanteen tutkinnassa | lentoposti.fi
Short summary in English:
The B737 registration LN-BYM (NAX5630) was flying the ILS 34 approach to Kittilä (EFKT), in Northern Finland, when at 3250 ft on the glideslope with autopilot engaged and flaps partially extended the aircraft started a sudden climb with full thrust, at the same time letting the airspeed decrease near stalling speed. The aircraft climbed 1500 ft during the incident before the pilots regained control.
The next approach was successful and no technical faults have been found so far in the aircraft.
Norway's Accident Investigation board (SHT) is investigating this incident together with it's Finnish counterpart, NTSB and Boeing. SHT has the FDR and some aircraft parts in its possession.
Some facts which may be irrelevant in this case: EFKT34 ILS G/S is 3.4 degrees steep, with typically tailwind conditions (no precision approach to 16 available), 2.5 km runway and often slippery runway conditions. Depending on time and day the airport may be manned either with an ATCO (TWR) or an AFIS person.
Any ideas from B737 pilots?
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Yes...it shouldn't take 1500 feet to "regain control".
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No TOGA below 2000ft RA on the 737 and Kittila has an elevation of about 600ft. Also, I would be surprised to see full thrust during a normal go-around; false glide-path?
Last edited by rudolf; 3rd Apr 2013 at 21:15.
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I have seen this once years before in a -900. I wrote it up after the landing and followed up with maintenance. No fault was ever found and we also came to believe it was due to a false glide slope. In level flight approaching the marker the G/S needle had just wiggled alive and the aircraft went off to the races in a climb. It can be easily controled by selecting AP off, but the flying pilot was a brand new ab initio FO. We climbed about 500 feet before I got him to release the yoke and let me get it back to altitude. Stuff happens. That is why they still put us in the pointy end.
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None of which should cause a steep climb and an 'airspeed decrease near stalling speed.' It remains to be seen whether this was a system or human failure and with the FDR etc it should not be long.
My first look would be at manual throttle, poor speed control and autothrottle 'armed' kicking at 1.3Vs with TOGA and autopilot disconnect followed by big wide Scandi eyes, but as I say, it will all be in the data.
My first look would be at manual throttle, poor speed control and autothrottle 'armed' kicking at 1.3Vs with TOGA and autopilot disconnect followed by big wide Scandi eyes, but as I say, it will all be in the data.
I had an incident, capturing the glide slope from above while in open descent, where the altitude window switched to the default upper limit (50,000'). The aircraft pitched up to climb, but as the power was at idle for the previous descent the aircraft washed off about 30 knots within a few seconds...
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Was the journalist in the flight deck..?
From the Norwgian AIBN:
ENGLISH:
On the 26th of December 2012, Norwegian Air Shuttle with flight number NAX5630 serviced a regular passenger flight from Helsinki airport Vantaa (EFHK) to Kittilä airport (EFKT) in Finland. The aircraft in use was a Boeing 737-800 delivered new to Norwegian Air Shuttle in 2011.
Enroute the flight was uneventful and the aircraft was established on the approach to runway 34. When the aircraft passed approximately 3,250 ft on the instrument approach (ILS) with flaps 5 and autopilot engaged, the aircraft started an unintentional steep climb with full engine power. The aircraft climbed approximately 1,500 ft and the airspeed dropped so that the aircraft came close to a stall. However the pilots managed to regain control of the aircraft. Some later a new approach was executed and an uneventful landing was made in Kittilä. After the incident, the aircraft has been flown on a test without any remarks.
The Accident Investigation Board Norway has access to the aircraft digital flight data recorder and some aircraft components. In corporation with the US National Transportation Safety Board (NTSB), Boeing and the airline, it is initiated an ongoing investigation as a result of the incident.
On the 26th of December 2012, Norwegian Air Shuttle with flight number NAX5630 serviced a regular passenger flight from Helsinki airport Vantaa (EFHK) to Kittilä airport (EFKT) in Finland. The aircraft in use was a Boeing 737-800 delivered new to Norwegian Air Shuttle in 2011.
Enroute the flight was uneventful and the aircraft was established on the approach to runway 34. When the aircraft passed approximately 3,250 ft on the instrument approach (ILS) with flaps 5 and autopilot engaged, the aircraft started an unintentional steep climb with full engine power. The aircraft climbed approximately 1,500 ft and the airspeed dropped so that the aircraft came close to a stall. However the pilots managed to regain control of the aircraft. Some later a new approach was executed and an uneventful landing was made in Kittilä. After the incident, the aircraft has been flown on a test without any remarks.
The Accident Investigation Board Norway has access to the aircraft digital flight data recorder and some aircraft components. In corporation with the US National Transportation Safety Board (NTSB), Boeing and the airline, it is initiated an ongoing investigation as a result of the incident.
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I had it twice on an -800, GS -roller coaster type- captured far beyond what the good practices dictate. The thing started to climb like it would never end and indeed the A/T were doing a very poor job at maintaining speed. The outcome: A/P disengaged and reestablished ourselves on the right path.
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This wouldn't have happened if the flying pilot had kept his paws on the wheel and thrust levers during final approach. Any Boeing A/P and A/T can INSTANTLY be switched OFF, or overridden with muscle power. 
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Miles out
Many moons ago I learned that there is a limit like max 25 nm out for the LOC and 17 nm for the GS. This is imho the earliest where you can receive reliable signals. I experienced something similar on the 747 as well but if you keep your hand on yoke and thrustlevers you just switch the damn A/P of instead of watching it trying to kill you.
If you don t understand the automatica at any moment revert to manual flying
If you don t understand the automatica at any moment revert to manual flying
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I had an incident, capturing the glide slope from above while in open descent, where the altitude window switched to the default upper limit (50,000'). The aircraft pitched up to climb, but as the power was at idle for the previous descent the aircraft washed off about 30 knots within a few seconds...
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I had an incident, capturing the glide slope from above while in open descent, where the altitude window switched to the default upper limit (50,000'). The aircraft pitched up to climb, but as the power was at idle for the previous descent the aircraft washed off about 30 knots within a few seconds...
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Rudolf,
TOGA is indeed available above 2000RA on later B737NG with flaps not up or G/S captured. If the AFDS remained engaged then it would have commanded only sufficient thrust for 1-2000fpm climb, and a speed of 182 kts with flap 5. The cause lies elsewhere I think.
TOGA is indeed available above 2000RA on later B737NG with flaps not up or G/S captured. If the AFDS remained engaged then it would have commanded only sufficient thrust for 1-2000fpm climb, and a speed of 182 kts with flap 5. The cause lies elsewhere I think.
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If it's related to GS capture, MCP altitude setting, etc, how does it even change 100' before the CVR hears 'click' and 'click'(sounds of A/P and A/T disconnecting)?
One of the worst things to watch is to see the a/c displacing from the intending flight path, especially fairly abruptly due to false GS capture, TOGA engagement, etc, and see the flying pilot try to figure out what mode the FMC/AP is in. Who cares? Turn it off, hand fly it along the desired flight path, and reestablish the appropriate level of automation.
'Click' 'click' is the fastest way to reestablish direct control of the airplane. Is it needed for most situations? No. Knowing how to work the FMC/AP is important. But equally important is understanding when manual control is required. Disengaging the AP when simple FMC/AP entries would fix the problem is not the goal either. Know the level of automation appropriate (hand flown, AP-V/S ALT HOLD, speed intervention, FMC-LNAV, VNAV, speed intervention, etc) and achieve the mode needed for the situation. IF the a/c isn't performing as desired/required YOU fix the problem.
Using the wrong level of automation seperates the men from the boys. Inappropriate mode use can be painful to watch.
One of the worst things to watch is to see the a/c displacing from the intending flight path, especially fairly abruptly due to false GS capture, TOGA engagement, etc, and see the flying pilot try to figure out what mode the FMC/AP is in. Who cares? Turn it off, hand fly it along the desired flight path, and reestablish the appropriate level of automation.
'Click' 'click' is the fastest way to reestablish direct control of the airplane. Is it needed for most situations? No. Knowing how to work the FMC/AP is important. But equally important is understanding when manual control is required. Disengaging the AP when simple FMC/AP entries would fix the problem is not the goal either. Know the level of automation appropriate (hand flown, AP-V/S ALT HOLD, speed intervention, FMC-LNAV, VNAV, speed intervention, etc) and achieve the mode needed for the situation. IF the a/c isn't performing as desired/required YOU fix the problem.
Using the wrong level of automation seperates the men from the boys. Inappropriate mode use can be painful to watch.
Last edited by misd-agin; 6th Apr 2013 at 13:37. Reason: replaced . with a ?