View Full Version : Do smooth Landings effect LDR in Big Jets?
Sheep Guts
25th Jun 2003, 06:34
This may be a silly one. But I watch quite alot of Jets land where I am based mostly US and Carib Carriers. And have noticed that they do fantastic smooth touch downs, but sometimes at a cost. They chew up the runway available ie. touching down 1000 -2000 feet past the touch down markers. Now this must effect stoping distance. I am wondering is this a major factor, as I see it daily and wonder one day there aint gonna be much black top left at the end :uhoh: .TO STOP when thye really need to.
Regards
Sheep
Mad (Flt) Scientist
25th Jun 2003, 11:35
Yes!
But as to how it affects it - that gets a little more complicated.
Actual Landing Distances are calculated based on analysis of flight test "Performance Landings" which are flow to a specific set of conditions. In general most normal landings will be less 'performance oriented' than these test landings (which is fine, usually there's runway to spare). The kind of landings you describe fall into that category.
Almost certainly they are requiring a larger 'air distance' than has been assumed in calculating the landing distances. However it's probably that the touchdown speed is actually lower than would be the case for a 'performance landing' - as the plane has spent more time decelerating in the air. Therefore the stopping distance may well be shorter.
I'd expect the overall effect to be that a longer total distance (including the airborne distance) is being used than the manual lists.
expedite_climb
26th Jun 2003, 02:20
Yes, particularly if you are a couple of knots fast, certain types will just float forever down the runway if you arent careful.
You then slam on the brakes and throw everyone about, and take 20 minutes taxying to the gate, because you floated so far, but thats ok if you did a nice landing .:p
Sheep Guts,
We are only permitted to plan operations to runways which are 40% longer than demonstrated in performance landings. Crews therefore know that they have that extra distance to play with.
Mutt.
Sheep Guts
26th Jun 2003, 08:12
Thanks guys for the responses
Its very interesting to get feedback. I thought it was a consideration. Just too me it seems if youhave some Runway to play with, here at Montego Bay there is an LDA of 7893ft/2405 Metres Runway 07 the most used. Why play with it .
I suppose the math on that works out. Would that give a A310 or A300 stuff to play with Mutt?
I play aswel I suppose, but Im in an Otter. :)
Regards Sheep