A37575
5th Jun 2010, 08:42
Whenever there is a serious aircraft accident we usually read about it on Pprune. Two years can elapse before the official accident report is published and in the meantime there will be be healthy debate by retired arm-chair pilots like myself and others genuinely wanting to learn from past accidents. Occasionally name-calling spoils a debate while it not uncommon to read accident reports that are muted to protect ethnic sensibilities.
There are significant flight safety lessons of interest to pilots who bother to trawl through Pprune forums. But someone still has to go to the trouble of putting this info on Pprune and not just the same contributors whose user names dominate flight safety discussions. Mea Culpa.
Most experienced pilots will have had at least one almighty fright in their flying career - yet understandably are reluctant to put pen to Pprune lest they be labelled with the dreaded accusation of being a "line-shooter". Lessons learned by these experienced pilots are thus often lost to the rest of us and especially to the younger generation of pilots brought up from CPL standard directly into fly-by-wire glass cockpit aircraft. That is a pity since they miss out on what could be vital flight safety information. The excellent reliability of modern airliners mean that rarely do events turn nasty on the pilot. But if something does go seriously wrong in a few seconds, the crew may be caught completely off guard.
For this reason, I thought that experienced Ppruners could do an awful lot of good by sharing with the younger generation of pilots a brief account of their one or more seriously close shaves. Cold hard facts where possible. When this thread eventually dies away as things do on Pprune, then what you have contributed may have helped prevent a similar close call. I'll start it off - and please remember it is not a line-shoot and maybe not that dramatic - but it sure frightened me for a couple of seconds:
In 1978, Agana US Navy airbase at Guam in the Marianna Islands of the SW Pacific, shared the facility with civilian operators. There are two parallel runways 6R and 6L. An ILS is on 6L and the runway is over 9000 ft long. To depart 6L, aircraft back track 6R full length and hold at ninety degrees to the final approach path on the taxiway joining 6R and 6L. From recall, the horizontal distance between the threshold of both runways is around 150 yards. It was common practice for traffic using the 6L ILS to side-step right to land 6R if weather permitted. This gave more efficient utilisation between military and civil traffic.
We were flying a B737-200 from Manila to Guam and cleared via the 6L ILS to side step right for 6R when visual. Cloud base around 1000 ft and dark night - wind calm. ATC cleared a PANAM aircraft to hold between 6L and 6R and be ready for immediate departure 6L once we had called side-stepping. After we became visual and turned slightly right away from the ILS in order to line up for 6R, ATC cleared PANAM for line up and immediate take off 6L.
There was no VASIS for 6R and once we were outside the ILS localiser the glide slope was obviously not usable. We were aware of a flashing beacon of the PANAM aircraft but because of lack of lighting could not determine if the aircraft was still holding on the taxiway, or in the process of lining up on 6L
Our approach was stabilised by 500 ft agl at Vref plus 5 and guess work for on slope. In fact we passed over the threshold of 6R about 80 feet. As 6R was 8000 ft there was no problem with landing length. At that point the situation changed dramatically.
Without any warning it felt as though the 737 simply fell out of the sky and the F/O sang out out "Bug minus 20". That was Vref minus 20. We experienced marked wing drops in both directions. I fire-walled the thrust levers and pulled back on the control wheel towards 15-18 degrees body angle up. Just as the aircraft appeared to hit the runway at high sink, the thrust cut in and we headed up and soon after we were back in cloud still at full thrust.
We were then radar vectored for another ILS with an uneventful landing; this time on 6L. Investigation revealed that the PANAM 747 was still on the taxiway a minute or so after being cleared for immediate take off 6L but delayed lining up. The aircraft had then opened up to break-away power on the taxiway just as we passed behind him at 80 feet. His jet blast caught us causing momentary loss of control. Because of night conditions we had been unaware of his exact position and thus never noticed the tail of the 747 pointing right at us as we passed close behind.
Lesson learned? Jet blast can cause a close shave just as much as windshear.
............................................................ ........................
There are significant flight safety lessons of interest to pilots who bother to trawl through Pprune forums. But someone still has to go to the trouble of putting this info on Pprune and not just the same contributors whose user names dominate flight safety discussions. Mea Culpa.
Most experienced pilots will have had at least one almighty fright in their flying career - yet understandably are reluctant to put pen to Pprune lest they be labelled with the dreaded accusation of being a "line-shooter". Lessons learned by these experienced pilots are thus often lost to the rest of us and especially to the younger generation of pilots brought up from CPL standard directly into fly-by-wire glass cockpit aircraft. That is a pity since they miss out on what could be vital flight safety information. The excellent reliability of modern airliners mean that rarely do events turn nasty on the pilot. But if something does go seriously wrong in a few seconds, the crew may be caught completely off guard.
For this reason, I thought that experienced Ppruners could do an awful lot of good by sharing with the younger generation of pilots a brief account of their one or more seriously close shaves. Cold hard facts where possible. When this thread eventually dies away as things do on Pprune, then what you have contributed may have helped prevent a similar close call. I'll start it off - and please remember it is not a line-shoot and maybe not that dramatic - but it sure frightened me for a couple of seconds:
In 1978, Agana US Navy airbase at Guam in the Marianna Islands of the SW Pacific, shared the facility with civilian operators. There are two parallel runways 6R and 6L. An ILS is on 6L and the runway is over 9000 ft long. To depart 6L, aircraft back track 6R full length and hold at ninety degrees to the final approach path on the taxiway joining 6R and 6L. From recall, the horizontal distance between the threshold of both runways is around 150 yards. It was common practice for traffic using the 6L ILS to side-step right to land 6R if weather permitted. This gave more efficient utilisation between military and civil traffic.
We were flying a B737-200 from Manila to Guam and cleared via the 6L ILS to side step right for 6R when visual. Cloud base around 1000 ft and dark night - wind calm. ATC cleared a PANAM aircraft to hold between 6L and 6R and be ready for immediate departure 6L once we had called side-stepping. After we became visual and turned slightly right away from the ILS in order to line up for 6R, ATC cleared PANAM for line up and immediate take off 6L.
There was no VASIS for 6R and once we were outside the ILS localiser the glide slope was obviously not usable. We were aware of a flashing beacon of the PANAM aircraft but because of lack of lighting could not determine if the aircraft was still holding on the taxiway, or in the process of lining up on 6L
Our approach was stabilised by 500 ft agl at Vref plus 5 and guess work for on slope. In fact we passed over the threshold of 6R about 80 feet. As 6R was 8000 ft there was no problem with landing length. At that point the situation changed dramatically.
Without any warning it felt as though the 737 simply fell out of the sky and the F/O sang out out "Bug minus 20". That was Vref minus 20. We experienced marked wing drops in both directions. I fire-walled the thrust levers and pulled back on the control wheel towards 15-18 degrees body angle up. Just as the aircraft appeared to hit the runway at high sink, the thrust cut in and we headed up and soon after we were back in cloud still at full thrust.
We were then radar vectored for another ILS with an uneventful landing; this time on 6L. Investigation revealed that the PANAM 747 was still on the taxiway a minute or so after being cleared for immediate take off 6L but delayed lining up. The aircraft had then opened up to break-away power on the taxiway just as we passed behind him at 80 feet. His jet blast caught us causing momentary loss of control. Because of night conditions we had been unaware of his exact position and thus never noticed the tail of the 747 pointing right at us as we passed close behind.
Lesson learned? Jet blast can cause a close shave just as much as windshear.
............................................................ ........................