Sunday, July 21, 2013

Density Altitude to the Max

I'm headed to Truckee, CA tomorrow and the forecast high temperature is 102F/39C.  Since Truckee is at 5901MSL, the density altitude is effectively infinite.

So how will I handle it?

First, I had originally planned a fuel stop, but the DUATS flight planner using the route I actually  intend to fly (rather than some impossible shortcut: see here) shows me arriving with a little over one hour's fuel remaining.  Less weight is a big help in this kind of situation, reducing stall speed and landing distance, so I don't want to have much more fuel than that.

Second, I will keep an accurate navigation log, and if things are not going as expected I will make the fuel stop anyway, but I won't fill the tanks.  It should be a little less than 2 hours from truck to Truckee, so I'll depart with 3 hours of fuel.

Playing with a Koch chart shows that my expected landing and takeoff distances are about 260% of normal.  Truckee's longest runway is 7,000' long, more than 4 times my normal landing distance.  With the high density altitude, though, touchdown true airspeed will be pretty high, so I'll need to brake carefully.  Again, less weight means less energy means less braking.

Checking the TAFs shows 8 - 15 knots of headwind on arrival; that's a big help, too.

Truckee is very noise sensitive and there is lots of glider activity; the airport publishes arrival and departure routes to help reduce the noise and keep the powered airplanes (in this case, me) separated from the gliders (someday, me).  I have downloaded the guide and put it into my tablet device using Dropbox.

I would like to depart for home with full fuel, but with density altitude this extreme I might decide to depart with less and stop someplace lower for more.  "Lower" is a loaded term, because fuel is relatively inexpensive at Truckee, so lower might be higher when it comes to money.  But safety trumps money.

The only remaining question I have, then, is what will the heat do to the fishing?

Tuesday, July 16, 2013


The compass points away from North, though sometimes it is close.

Its pole is not the Pole; when between the two it points the other way.

Magnetic spots on Earth attract its needle, too.

By day in sunlight the pilot notes the difference, but at night in cloud a different tale is told.

The difference between the mountain pass and the mountain is but a handful of degrees.

And the craft attracts the needle to itself.

Literally ironic.

Monday, July 8, 2013


[Another product of my attempt to redefine the problems of flying in terms of essence and finesse.]

Gravity varies in unexpected ways.

How can this be so?  Newton saw that a universal constant governs its effects.

How many universals do we work with in a day?

Yet gravity is strong in Minnesota, weak in high Peru,  its pull enough displaced to lead a craft astray.

For the universal constant is but one factor in its pull.

Mass and distance affect the force as well.

(Einstein said that mass effects the force, but that effect is relatively minor to the craft.)

The mass below the surface varies.  There is no irony here: in some places miners dig for ore, in others for something lighter, it being not the case that irony is everywhere.

And so in practice down is not the opposite of up.

The craft's lift does not oppose its weight directly.

A tiny change in finesse ensues.

All else being equal, when the engine fails, fly toward something soft, even if it lay unseen beneath the grain.

Friday, July 5, 2013

Experiencing Experience

There has been a lot of debate recently about pilot experience, with an FAA initiative to increase the amount of flight experience needed to be eligible for flying in an airline cockpit.  Some recent experience has got me thinking about this.

I recently had a chance to work with a CFI candidate who is a graduate of a Big Name Aviation University.  At first we were only doing ground instruction, and his depth of knowledge is absolutely amazing!  I can't remember the last time I talked with anybody, at any level, who had as much knowledge about aircraft, weather, regulations, procedures, well, everything!  If by some bizarre chance I ran across some fact or concept that he hadn't seen, he absorbed it immediately.

Then we moved on to flying.  His regular instructor had not done short field operations with him, and this is one of my favorite "tests."

When I was a Chief Instructor this is what I asked people to do on the interview flight.  Very few (maybe none) did a a good job.  There many kinds of mistakes.  Some dragged the airplane in, forgetting that a short-field approach needs to be steep in order to pass over the obstacle.  Some were too slow to get the airplane configured for landing.  Some were flustered by the presence of a control tower.  Most had inadequate airspeed control and floated excessively.  Many forgot to brake.  Nobody applied aerodynamic braking.

And nobody knew how to correct for gusts (add half of the gust term and expect extra float).

You get the picture.

Our BNAU graduate was better than all of these, but still not perfect, and that surprised me.  The patterns were erratic, and aircraft configuration varied too much.  But the final approaches were appropriately steep, and the touchdown was on the touchdown point.  

I was confused by the disconnect between book knowledge and practice, although in retrospect I should not have been.  The candidate just doesn't have enough flight time to smooth this maneuver out. Nobody with his level of experience really could.

I was reminded by the examiner's comment as he handed me the pink slip for my ATP: ``You fly much better than someone with 200 hours of multi time."  And that was for a bust!

Head knowledge enhances hand knowledge, but hand knowledge only comes about in one way: practice.  Practice.  Practice!

They say that it takes a rookie NFL quarterback 20 games to become effective.  Think about that: a rookie NFL quarterback has spent his whole life as the best athlete he knows.  His talent is enormous.  But time behind center is like time at the yoke, and it takes a certain amount to get there.

So, should airlines allow pilots with 250 hours into the cockpit as first officers?  That's 250 flight hours, Commercial, multiengine, instrument rated.  Maybe 10 hours of multi time?  No actual IFR time?  No approaches to minimums?  No missed approaches?  Maybe even no winter flying experience?

My answer: No!

But your mileage may vary...