V ref vs. V approach

[RubberNeck]

Got into a discussion the other day where one of my fellow pilots said I landed (touch down ) to fast. I normally use Vref +10 and carry that to just before touch down throttles closed on the runway, so i'm usually +5 on the R/W unless the situation requires more or less "short r/w or gusty conditions."
This fellow routinely will fly ref+0 and touch down Vref -5-10 ....what the consensus????

Thanks
RN

 

[bigsky]

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.

 

[ultrarunner]

Unless wind conditions dictate, if you're flying Vref +10 and not going to idle until touchdown, you're using WAY more pavement than necessary. Are you even making the touchdown zone?

At 50', Vref, close 'em. Unless of course Vref adjustments are dictated due to wind conditions.

 

[Fokkerflyer]

What kind of airplane? Recommended approach speeds vary by aircraft, based on wing design. Stick to what the manufacturer recommends, including gust correction.

 

[Spooky 2]

Unless wind conditions dictate, if you're flying Vref +10 and not going to idle until touchdown, you're using WAY more pavement than necessary. Are you even making the touchdown zone?

At 50', Vref, close 'em. Unless of course Vref adjustments are dictated due to wind conditions.

I'm not so sure that closeing the throttles at 50' is the best procedure, especially if your at Vref. Mybe I read something into your post that did not mean but I believe that if you were at Vref+5 at 50' and simply closed the throttles, assumming a no wind condition you would run out of airspeed prior to touchdown. Case in point from aprevious post talked about the MD11. I believe the AT start a power reduction at 47' when doing a Autoland and the B767-300 does the same thing around 30' so you can a simple "close'em" at 50' might not work for all aircraft. As for the corporate guys in the GV' BB700' I'm clueless but probably already new that anyway.

 

[ultrarunner]

I'm not so sure that closeing the throttles at 50' is the best procedure, especially if your at Vref. Mybe I read something into your post that did not mean but I believe that if you were at Vref+5 at 50' and simply closed the throttles, assumming a no wind condition you would run out of airspeed prior to touchdown. Case in point from aprevious post talked about the MD11. I believe the AT start a power reduction at 47' when doing a Autoland and the B767-300 does the same thing around 30' so you can a simple "close'em" at 50' might not work for all aircraft. As for the corporate guys in the GV' BB700' I'm clueless but probably already new that anyway.

I'll have to dig out Part 25, but I believe IF you want to make your published landing distance numbers, if that's important, then I believe that is based on the aircraft arriving at 50' feet, at ref with thrust levers at idle. A brainiac will chime in for sure to correct me.

Turbojet aircraft are not meant to be flown under power at ref+10 to touchdown. Now, you can do it, it's all about how much pavement you have in front of you and how much you're willing to leave behind you.

But keep that in mind one nasty rainy night when you're landing on runway 6 in TEB and you're at ref +10 at touchdown and then close the power levers.

I agree however in that some planes tolerate this practice better than others. Falcon drivers and straight-wing Citation drivers don't sweat Vref +10 NEARLY as much as a Lear driver, since the former has Vref of say 110 kts vs 135 knots.

You start adding 10 knots to ref speeds that start at 135 or 140 you better have some serious pavement in front you.

 

[G100driver]

I was alway taught to cross the fence at ref+5(or more for gust factor) and touch down on ref. Anything more than ref and you might as well not use your landing distance charts.

Now I am not that good, so I always use the 1.67 factor. After all, if I run off the runway, it sounds better at the hearing. Now that 91K is coming into effect I will probably switch to that.

 

[Rabble]

Vref is, by definition, 1.3 VSO. Tell the Lear driver to look at the AOA gauge next time he's flying at Ref +0. It's WAY in the green. Plenty of kinetic energy left for flying.

If you want to be at Vref +10, fine. But don't add a few more knots for the wind, and a few more for the wife and kids, and a few more for grandma...

On speed, on centerline, in the touchdown zone. Every time.

 

[ackattacker]

Again some braniac will surely chime in but my understanding is that per certification requirements the landing distance will be met with ref -5 to +15 at at a threshold height of 30ft. Now I'm really no expert but I typically split the difference and aim for +5.

 

[ultrarunner]

Vref is, by definition, 1.3 VSO. Tell the Lear driver to look at the AOA gauge next time he's flying at Ref +0. It's WAY in the green. Plenty of kinetic energy left for flying.

I am a Lear driver. And that's why I don't arbitrarily start adding knots to computed ref.

As you said, plenty of energy to fly at ref, unless wind conditions dictate otherwise.

 

[RubberNeck]

The plane in question is a Falcon 900EX

Thanks
RN

 

[2EASYPilot]

The plane in question is a Falcon 900EX

Thanks
RN

Wiping the power off a heavy 900EX at ref and 50ft is something I usually avoid...a little extra speed is preferred.

 

[avbug]

Holding Vref + 5 or 10 isn't necessary, nor are your landing numbers valid if you do. Touching down at or below Vref is fine. Excess speed must be dissipated somehow. You can do it by flying on speed, or using excess braking and reverse thrust unnecessarily. If you need extra speed on the approach use it, but merely flying higher because you feel like an extra margin is helping...is not.

Tell the Lear driver to look at the AOA gauge next time he's flying at Ref +0. It's WAY in the green. Plenty of kinetic energy left for flying.

AoA doesn't necessarily equate to kinetic energy. You can have that gauge in the middle of the green arc sitting on the ground with no speed and no airflow...and zero kinetic energy. Alpha tells you about aerodynamic condition, not energy.

 

[slotationdriver]

[QUOTEAt 50', Vref, close 'em. Unless of course Vref adjustments are dictated due to wind conditions.
__________________
][/QUOTE]
This is how they figure the landing distance for the Ultra. Go into a short strip with an ultra, you will want to follow this. Last week at simuflight they said that in ice you must fly REF + 8 in the ultra minimum. anyone heard different.

 

[Seadogrun]

I believe the landing distances are derrived from chopping power at 50 above the end of the runway. This way they get the lowest possible landing distances. The test pilots are NOT worrried about pax comfort and probably land pretty hard and go to max braking. Pilots must keep this in mind when choosing to go into a short runway near the max. runway required. On one hand we can "cheat" and cross the runway threshold below 50, but on the other hand we most likely(depending on type) are not chopping power at 50 ft.

Another note: Not all aircraft does Vref = 1.3 Vso. For instance in the Challenger it is 1.4 Vso.

 

[DrProc]

Just remember, there are more accidents being fast and running off the end of the runway then there are getting too slow and landing short of the runway.

 

[deadstick]

scroll to 7/1/06, there's a nice chat about Vref...

APTAP

 

[ksu_aviator]

I got in an argument with an examiner about this very point. I let him win the argument, but I verified my answer shortly after the check ride and I was correct.

I checked in the AFM under the performance section. It referred me to a chapter that explained the landing procedure. I suggest that you read that section for your aircraft because it may have some variences.

For the Lear 20's 30's and 45 the AFM gives a specific hat, speed and throttle location. They list 50 feet (55 in the 45) on Vref and throttle levers biskly moved to idle. Landing is then accoplished with minimal float and maximum breaking (thrust reversers are not factored into the landing performance).

 

[Waldom]

Performance calculations are based on Vref and decreasing at a point 50' over the threshhold. I don't believe anything is mentioned regarding a power setting in F.A.R. 25.

 

[gunfyter]

This fellow routinely will fly ref+0 and touch down Vref -5-10 ....what the consensus????

Thanks
RN

I vote for ref -5-10. Has worked for 25 yrs for me.

 

[TXDA2000]

Try this in any Falcon on an EMPTY leg, with a LONG runway.

Cross the fence normally, roundout and flare till the wheels are at 1 ft. Hold the aircraft at this altitude as long as you dare.

In the 2000, I've never had the guts to go below 80 kts. Still, below 90 it is very solid. This is from a ref of around 110.

The 2000 definitely likes the 50 ft at ref, power to idle approach. I can't imagine the 900 being much different with the same wing and higher weights/speeds.

 

[MauleSkinner]

Performance calculations are based on Vref and decreasing at a point 50' over the threshhold. I don't believe anything is mentioned regarding a power setting in F.A.R. 25.

It's not in Part 25, but as KSU pointed out, the individual manufacturers use slightly differing techniques, usually published somewhere in the airplane manuals (not necessarily the AFM). They may include power, or power reduced to idle at a certain point.

I don't know about the Falcon 900's, but the Falcon 10's were final and touchdown at Vref, and IIRC, there was something about a descent rate (600fpm comes to mind) at touchdown...IOW, no "greasers"

Fly safe!

David

 

[Seadogrun]

It's not in Part 25, but as KSU pointed out, the individual manufacturers use slightly differing techniques, usually published somewhere in the airplane manuals (not necessarily the AFM). They may include power, or power reduced to idle at a certain point.

I don't know about the Falcon 900's, but the Falcon 10's were final and touchdown at Vref, and IIRC, there was something about a descent rate (600fpm comes to mind) at touchdown...IOW, no "greasers"

Fly safe!

David

A good point to make is that the way they do it for flight testing is not a realistic way to fly everyday. They do it that way to get the smallest landing runway required as possible at least partially for marketing reasons. The result in flight testing of aircraft is very firm/hard landings, but they stop in the shortest distance. My approach is to achieve safety first then pax comfort, but if I can get both I'll do it that way. I also wouldn't land on a runway that is at the minimum required. I like the 135 landing numbers which will allow you to land safely and smoothely.

 

[2EASYPilot]

Try this in any Falcon on an EMPTY leg, with a LONG runway.

Cross the fence normally, roundout and flare till the wheels are at 1 ft. Hold the aircraft at this altitude as long as you dare.

In the 2000, I've never had the guts to go below 80 kts. Still, below 90 it is very solid. This is from a ref of around 110.

The 2000 definitely likes the 50 ft at ref, power to idle approach. I can't imagine the 900 being much different with the same wing and higher weights/speeds.

You would not think it was different but it is...we fly both and the 2000 is like a cub compared to the 900EX.

 

[AV8OR]

On app, ref +5-10 dep on a/c, slowing to ref at the runway tdz, centerline. IMO

 

[Waldom]

It's not in Part 25, but as KSU pointed out, the individual manufacturers use slightly differing techniques, usually published somewhere in the airplane manuals (not necessarily the AFM).

I should know better than to pull an answer out of my memory bank. I don't have a copy of F.A.R. 25 to consult on my bookshelf. [I usually check references before a post in an attempt to keep my foot out of my mouth].

 

[CL600Pilot]

I got in an argument with an examiner about this very point. I let him win the argument, but I verified my answer shortly after the check ride and I was correct.

I checked in the AFM under the performance section. It referred me to a chapter that explained the landing procedure. I suggest that you read that section for your aircraft because it may have some variences.

For the Lear 20's 30's and 45 the AFM gives a specific hat, speed and throttle location. They list 50 feet (55 in the 45) on Vref and throttle levers biskly moved to idle. Landing is then accoplished with minimal float and maximum breaking (thrust reversers are not factored into the landing performance).

That's the same way Cessna does basically - the Cessna charts (at least in the Ultra and XLS) are predicated on crossing the threshold at 50' agl, at Vref, and throttles at idle. This of course means that you will be slower than Vref when you actually touchdown. The airplane doesn't fall out of the sky at Vref.......or even at Vref-10.

 

[DoubleB]

Throttles to idle at 50ft - WOW!!

For what it's worth, I'd be very careful of blindly advising anyone to "go to idle at 50 ft". I assure you that even at ref plus 10 there are some aircraft that will come out of the sky like a sack of SHIITE if you do that.

For my money, ref plus 10 on the approach, power reduction as appropriate to arrive on the runway at ref in the touchdown zone.

WHen you go to idle depends on 1) aircraft type (wing loading is a big factor), 2)weight and 3) wind conditions.

Go to idle in a 767 or a G200 at 50' and ref plus 10, and I assure you that the results will be very unpleasant.

 

[Raskal]

For what it's worth, I'd be very careful of blindly advising anyone to "go to idle at 50 ft". I assure you that even at ref plus 10 there are some aircraft that will come out of the sky like a sack of SHIITE if you do that.

For my money, ref plus 10 on the approach, power reduction as appropriate to arrive on the runway at ref in the touchdown zone.

WHen you go to idle depends on 1) aircraft type (wing loading is a big factor), 2)weight and 3) wind conditions.

Go to idle in a 767 or a G200 at 50' and ref plus 10, and I assure you that the results will be very unpleasant.

I have to agree with some of the above, I routinely cross the threshhold in the hawker 1000 at ref and end up touching down (closing the throttles at around 30ft) at ref -5 to -10 with no issues (in reasonable tolerable wind conditions), any more speed and the float is a bit much. However, try this in a hawker 700 and the results are quite often unpleasant for all aboard, that thing is a brick.

I haven't flown the falcons, but I'd have to think it's based on individual aircraft characteristics (regardless what part 25 says). As safe and smooth as possible, with safety being primary is the goal. If your technique works, it works-but as I learned quickly, adjust it for the aircraft-not a general rule.

 

[BenderGonzales]

I believe that the original poster was addressing those pilots who bug Vref and Vapp, then fly Vapp plus additives.

If you are flying Vapp plus a gust factor, plus a few knots for grandma and the kids... you are crossing the fence at Vref +20 or so. That's a lot of kinetic energy to rid yourself of in the flare, and the dissipate with brakes before the end of the runway.

My operator requires a stabilized approach in VFR conditions by 500 AGL. Vref plus 1/2 the gust factor, configured, and engines spooled. If those conditions aren't met, a missed approach is required.