V ref vs. V approach

[GVFlyer]

The method we used when certifying GV landing data at Roswell, NM was based on the following criteria.

Gear down, flaps 39 degrees, and high idle prior to touchdown.

Vref at 50 feet, 3.5 degree descent path at 50 feet, thrust levers to idle, 8 foot per second sink rate to touchdown. Maximum braking, autoground spoilers or manual ground spoilers, engines auto low idle at touchdown.


GV

 

[Raskal]

The method we used when certifying GV landing data at Roswell, NM was based on the following criteria.

Gear down, flaps 39 degrees, and high idle prior to touchdown.

Vref at 50 feet, 3.5 degree descent path at 50 feet, thrust levers to idle, 8 foot per second sink rate to touchdown. Maximum braking, autoground spoilers or manual ground spoilers, engines auto low idle at touchdown.


GV

Just out of curiosity, how do you guys get your 3.5deg glideslope info? Do you have an indication or is it a derived speed/vsi number?

 

[ksu_aviator]

Raskal...I believe he said "8 Foot per Second"

 

[HA25]

I guess I would say that with bigger airplanes excess speed can be an issue. I am trying to remember but I think the number stated in the md-11 is it takes an additional 2000 feet of ry if you hold the airplane off the ground to bleed off an extra 10kts of airpseed. touching down 10 kts fast takes an additional 400-600 feet wet or dry.
that being said I can say it is not a great idea to carry more than you need but I am not a big fan of getting slow either. Planning on ref + 0 sounds like a problem should you encounter any type of shear.
I have never seen any plane or operation that didnt use a minimum of ref + 5 as approach speed.

I agree.. I've noticed (in my short time on it), that the MD-11 already has high ref speeds... sometimes in the mid 160s.. so the last thing you need to do is fly faster... I used FMS speed to maintain the "Foot+5" or Vapp unless there is a WindSheer or other reason to modify..

That said, even when I flew Citation X, V and other aircraft, I always tried to fly Ref+5 max as I noticed two problems with flying fast... 1. you eat up too much runway/brakes. 2. you are forced to go to idle earlier in your landing flare which is bad technique, especially if you are needing to go around, and are flying a jet with fans that take a bit of time to spool up...

 

[Raskal]

Raskal...I believe he said "8 Foot per Second"

Doh...sorry, reading ADD...Look! There goes a squirrel!