Originally Posted by
retired guy
Does anyone in this thread actually fly a long haul commercial jet? I often wonder at some of the comments?
people seem to make statements rather than ask questions for the experienced aviators to answer eg “ some kids doused in fuel is better than a smoking hole”!
Our guidance is different -
1 overweight landings even up to max takeoff weight are approved in an emergency. Example fire on board.
all that’s required is an inspection.
1. agreed
2 dumping fuel gets you down to max landing weight , or near it, and is recommended if possible.
2. fuel jettison *if necessary*. Given #1 it's often not necessary.
3 dumping should be conducted at higher altitudes >6ooo ft and over non built up areas and in a straight flight path
3. our guidance is 'not in a circular pattern'. Straight flight path is not required.
4 weight is not critical to safety generally unless on a short limiting runway. On a large jet 2 tones of weight = approx 1 knot.
4. on the 777 approach speed reduction is 1 kt per 7,000 lbs. Roughly 3 tonnes.
In short the decision to land overweight depends on the severity of the emergency and the runway length/conditions.
I can think of no excuse at all for dumping so low as shown in the video.
5. agreed. You're going to reduce your approach speed 2-3 kts for the additional time they dumped below 5000'? Every minute of dump from the center tanks if reducing your approach speed by approx. .8 kts. Each knot of additional approach speed is less than 100' of required landing distance (actual distance is .6 of required). The math works out to an increased distance of approx. 35' per knot actual and 60' per knot required landing distance. Aimpoint alone with be a bigger factor in the actual landing distance used. They gained a reduction of approx. 150' actual distance used and reduced their required landing distance by approx. 150'.
As for the hypothesis that “they forgot”- well OMG. Has pilot training/skills set really sunk that low? I know that in the next 25 years 500,000 pilots are required mainly in developing world. Now there’s a challenge.
R Guy