18kt crosswind component on a 3800' runway pushing it?

[MidlifeFlyer]

Re: 18kt crosswind component on a 3800\' runway pushing it?

[ QUOTE ]
Any mountainous airport in the summer 3800 ft isn't that long anymore. Try Flagstaff, AZ on a hot summer day! You'll see what I mean, and you'll wish that crosswind was a headwind!

[/ QUOTE ]You mean like Colorado's Glenwood Springs ( 5916 MSL, runway length 3305) or McElroy Field (7400 MSL, runway length 5540)?

I fly and teach in Colorado (including mountain checkouts) so I definitely agree that I'd much rather have an 18 KT headwind than an 18KT crosswind.

But I still don't understand what density altitude has to do with how much crosswind you can handle. Given the same headwind component, I haven't notice my rollout in a crosswind landing being any longer than my rollout without a crosswind.

 

[Eagle]

Re: 18kt crosswind component on a 3800\' runway pushing it?

[ QUOTE ]
But I still don't understand what density altitude has to do with how much crosswind you can handle. Given the same headwind component, I haven't notice my rollout in a crosswind landing being any longer than my rollout without a crosswind.

[/ QUOTE ]

the answer is in your question.

Why is density alt an issue because you will need more runway (or less) right.

is this a function of the runway? No
it is a function of the performace of the aircraft.

at higher dens alts the performence of the acft is reduced. this includes response time from control input to result.

a 172 that can;t get out if it's own way at 5000ft agl, will have even more of a problem at 7-10000ft Dens alt. if you need to abort on the approach, you are relying on the ability of the aircraft to respond as needed to save your cookies....

I'd rather go missed at 200ft ......

 

[MidlifeFlyer]

Re: 18kt crosswind component on a 3800\' runway pushing it?

[ QUOTE ]
the answer is in your question.

[/ QUOTE ] Perhaps you misunderstand my question.

Of course you use up more runway at high density altitude. That's basic.

Unless I misunderstood it, the post I was questioning [ QUOTE ]
What's the density altitude? If it's not too high, that should be okay for you.

[/ QUOTE ]
suggested that given the same density altitude conditions and the same airplane, a pilot landing with a 0 headwind component and a 15 KT crosswind component will use up more runway that a pilot landing with a 0 headwind component and a 0 crosswind component.

I've never heard that before, never noticed it when flying at high density altitude airports, and have never seen a notation about increasing the distances based on the amount of crosswind in a landing performance chart.

 

[E_Dawg]

Re: 18kt crosswind component on a 3800\' runway pushing it?

If you have the same indicated airspeed, wouldn't control response be exactly the same regardless of density altitude...?

You're TAS and probably groundspeed will be much higher, but control response would have to do with the airflow over the surface, which IAS would show.

 

[Eagle]

Re: 18kt crosswind component on a 3800\' runway pushing it?

[ QUOTE ]
If you have the same indicated airspeed, wouldn't control response be exactly the same regardless of density altitude...?


[/ QUOTE ]

If you make me start to think about this I am going to get angry

Yes the IAS will be higher and the control repsonse the same.

THat is assuming you are carrying a faster than normal Approach speed right?

So does one keep the speed up to a higher rate when dealing with a higher DA? Or is it that as the DA increases the air is thinner, so you need to use more energy (relative to HP) to accomplish the same TAS/IAS? and if the air is thinner, then doesn't it suppose there is less "air" to react with the control surfaces?

 

[E_Dawg]

Re: 18kt crosswind component on a 3800\' runway pushing it?

[ QUOTE ]
and if the air is thinner, then doesn't it suppose there is less "air" to react with the control surfaces?

[/ QUOTE ]

At extreme risk to myself...

Sure, but the IAS measures more or less the # of air molecules flowing over the wings. If it reads, say, 100 kts, then you've got 100 kts worth of air over those wings regardless of altitde.

Since control response is dependant on how much air is moving over them, it'd be the same for a given indicated airspeed... regardless of density altitude.

For the same true airspeed, you'd have less air the higher you go because your IAS would have to be less.

You'd just keep the approach indicated speed the same though...

How I understand it anyways!

 

[Eagle]

Re: 18kt crosswind component on a 3800\' runway pushing it?

well I guess that makes sense the issue is you need a higher TAS to make the acft perform as it does at a lower DA.

If we agree, and I think we do,

then doing a Xwind landing at a higher than normal TAS, and one would assume higher GS, is going to shrink your margins a little duing the landing. right?

 

[MidlifeFlyer]

Re: 18kt crosswind component on a 3800\' runway pushing it?

[ QUOTE ]
At extreme risk to myself...
[snip]
You'd just keep the approach indicated speed the same though...


[/ QUOTE ]You understand it correctly. You fly the exact same approach IAS at high density altitude airports as you do at sea level. In non-molecular terms, the pitot tube reads impact air pressure. So do the wings. The same amount of impact reads the same. You just need a higher TAS to get the same impact.

That's true for all load-limited speeds.

 

[E_Dawg]

Re: 18kt crosswind component on a 3800\' runway pushing it?

[ QUOTE ]
then doing a Xwind landing at a higher than normal TAS, and one would assume higher GS, is going to shrink your margins a little duing the landing. right?

[/ QUOTE ]

I don't think it would... reason being the wind speed is also 'indicated'.

If the most you're airplane can do is say, 20 kts (not max demo, max period), then it will do 20kts at 0' or 10,000'. The only thing that would change is your TAS.

But hell, all that matters is how much rudder you need vs how much you have on final anyways...

 

[Eagle]

Re: 18kt crosswind component on a 3800\' runway pushing it?

I agree, but my point is the landing zone remains the same. a 50x3500 runway is still 50X3500 regardless of DA. , the margin for error at higher TAS would be less

 

[pkloop]

Re: 18kt crosswind component on a 3800\' runway pushing it?

When I was training for my private we had winds at 26 kts
s
y
I was landing !!!!!a
w
e!!!!!!!
d !!!!!!!
i !!!!!!!
s 05
On our last approach tower finally changed the active and we did a go around. Man my instructor was sweatin bad!!!
Yes you run out of rudder so line up sideways and blow onto the runway. Worked for me.

 

[pkloop]

Re: 18kt crosswind component on a 3800\' runway pushing it?

It screwed up my post? I wrote sideways well...sideways