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A question about touchdown

Pro Member First Officer
Bartholomew First Officer

Suppose your Vref speed is 130 knots. You fly at that speed until the very flare but what do you do then? Are you supposed to touchdown at 130 knots (which means fly a few knots faster on approach), or should you reduce the power to idle on flare, reduce the rate of descent and slow as much as the altitude between the flare and touchdown allows. Because if you need to touchdown at 130 knots that means you should even increase power slightly to maintain 130 on flare! However, if you slow down there's no point in having a specific Vref speed. But Rod tells you in flying lessons to always decrease power to idle upon touchdown!

I'm confused! Question

Pro Member Chief Captain
pilotwannabe Chief Captain

To my knowledge Rolling Eyes the Vref is the speed the aircraft should be at 50ft above the runway, i.e just prior to flaring Wink

This speed is calculated by pilots as 1.3 of Vso...Vso being the speed at which the craft will stall Wink

Pro Member Chief Captain
Jonathan (99jolegg) Chief Captain

Vref is the landing speed. It is meant to be as specific as possible. It is used when approaching an airport because it is hard to tell your speed when you are flying at a couple of thousand feet on approach. When flying close to the ground at 50 feet, the attention if focused more on judgement outside of the aircraft and visual cues combined with the instruments. What I am getting at is, yes, the Vref is very important and should be maintained as closely as possible, but when you reach 10-50 feet, you cut power and flare, from Vref so yes, your landing speed will probably be a few knots slower - but there won't be a significant difference.

Hope it helps Wink

Pro Member First Officer
Bartholomew First Officer

Yeah, thanks! It reassures me, Jolegg...

I just never knew about 1.3 of Vso... And why would the pilots need to calculate that when there's an FMC to do it automatically, or at least a speed chart... But I guess it's safer to do it the old way!

Very Happy

Pro Member Chief Captain
Jonathan (99jolegg) Chief Captain

Its not done manually, I think PW was just pointing out how you can work it out for the sim for aircraft without an FMC Wink

Pro Member Chief Captain
pilotwannabe Chief Captain

99jolegg wrote:

Its not done manually, I think PW was just pointing out how you can work it out for the sim for aircraft without an FMC Wink

Yes

Although whats the difference between an FMC and a calculator really Laughing

A few more buttons maybe Very Happy

Pro Member Chief Captain
Jake (JarJarBinks) Chief Captain

i always cut engines to idle when i pass over the threshold

Pro Member First Officer
mcmxl First Officer

If you do no cut power won't the plane tend to float?

Pro Member First Officer
PH First Officer

Vapp will be approach speed as you cut the power (depends on AC type) but generally threshold- speed will then bleed back to Vref due to drag overcoming thrust.

Pro Member First Officer
Bartholomew First Officer

JarJarBinks wrote:

i always cut engines to idle when i pass over the threshold

I think when you pass over the theshold you're still a bit too high, so if you flare the aircraft might slow down too much and the VS can suddenly increase (below zero) causing you to drop onto the runway.

Scinfaxi Guest

What's the deal with the Learjet? On approach if you engage the air brakes (spoilers) w/e you want to call them, the plane goes up? Why is that? Doesn't that defeat the purpose of an airbrake? I find the Leajet increasingly hard to fly, it's annoying. Also on take off with all trim central, the plane climbs really fast and i find myself adding downward pressure. What's the deal with that? ANyone else have a clue what im talking about ? or is it just my lack of skillz?

Pro Member First Officer
PH First Officer

I would not say a lack of skills but really you need a good understanding of powered flight to really appreciate why things happen. Additionally it would be beneficial to spend some time in the Cessna before jumping into the lear....even with experience it is not the easiest to hand fly.
First of all spoliers should not be used on the approach, certainly below 1500ft AGL. Very briefly the reason you "balloon" when selecting spoilers is most probably down to the fact you are doing high speed. The spoiler will act as the elevator does, initiallycreating an upwards pitching moment...this needs to be anticipated and reacted to by applying slight forward pressure on the control column. There is much more to it but I hope this helps.
As you accelerate the wings create more lift etc etc therefore you need to trim once the airspeed settles down this will relieve the need for continuous forward pressure on the control column. Go to lessons to learn more.

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