Airline Flying 101: Anatomy of a Landing.
So, where does the planning for landing actually begin? In cruise? Near the top of descent?
It’s first thing in the morning, as soon as the alarm goes off–you’re thinking about the weather at your destination. That’s the deal: you know the jet, you know your own skills, you can count on your First Officer’s skill level–that’s a given at American Airlines–so what’s the wild card? The weather.
Having said that, let’s clarify this: we really don’t care about the weather–we care about the change. That is, the trend: what is progressing, and how fast?
The weather report is a snapshot, too soon to be history. And the forecast is a guess, really no better than your own–if you can detect the trend and the rate of change. Now, it’s true that pre-flight planning is based on both the snapshot and the prediction–but as a pilot, the only thing that really matters is how the weather is changing. Because real life in flight–unlike plans–is all about change, and so is weather: it’s never static.
So we’re pulling up the destination weather at regular intervals, but not to decide what we’re going to do when we get there. Rather, it’s to compare how the weather changes during the enroute time in order to understand what the weather is doing–how it’s changing, therefore how the air mass we’ll need to navigate is actually behaving.
Because it’s not like “the good old days:”
Halfway across the Pacific Ocean, fill ‘er up again against the possibility of bad weather in Korea. Weather data was harder to come by and so there was little or no way to get a string of accurate weather data comparisons in order to plot the changes and the trends.
When hours and thousands of miles later we did get close enough to Japan to pick up weather data for Korea, decision time: bad weather? Glad we have the extra gas. Good weather? Dump the extra USAF issued gas in the Sea of Japan and land in Seoul lightweight.
Those days are long gone.
And in the airline world, we have other things to tend to enroute anyway.
Well yeah, there’s that: dinner, maybe a sundae to deal with too. But more importantly, it’s time to line up the static facts for landing so as to have them firm in your mind in order to play them against the weather change when you’re finally on approach.
First, aircraft weight. You can predict the enroute burn pretty well, add that to the zero fuel weight and you’ve got the basis for your approach speed. Now, determine the worst case landing distance by taking the weight to the correct chart to determine the best case landing distance.
Then, determine the corrections for degrading factors: runway surface (wet, icy) and winds (tailwind and crosswind). Take the runway headings of the likeliest approaches and determine the wind angles and the tailwind penalties for for each. Now, get those azimuth ranges (deviation from centerline) set in your head and the landing distance incremental additive for each (for example, runway 4, the tailwind starts over 130 degrees or 310 degrees) so two things you need in your head: what’s the distance per knot, and based on the landing distance (worst and best case) what’s the max number of tailwind knots you can take. Ditto the crosswind.
And what’s your plan if any limit gets even close? Got that all in your hip pocket? Good. Tell the other guy.
I hate the word “brief,” which every aviator uses when they really mean “verbal walk through.” But that’s what you do a hundred miles out, a verbal walk through. By then, the field conditions are about what you can expect for landing because you’re about 30 minutes out.
So your verbal walk-through includes the approach procedure, plus the numbers (weights, stopping distances, penalties and runway options) and what you plan to do. Also, it’s good common sense to ask the other guy to do all the calculations separately and compare.
Now you both have the plan in your hip pocket, you both are following the plan rather than making it up as you go, and both confusion and ambiguity are reduced on approach.
Now, just get the small details firmed up in your head: wet runway? Windy? Firm touchdown? Speed additives for various contingencies? Brake settings? Know what you’re going to do–and tell the other guy.
So there you have it. Plot the weather trends in your head from wake-up to final approach. Know the static factors such as gross weight, stopping distance, wind angles and tailwind values plus the incremental corrections, flap settings and approach speeds, then play them against the dynamic factors such as winds, temperature, precipitations, runway length (prepare for a last second runway change!) and surface conditions.
The landing plan is one big, complex balloon animal: you squeeze one part, another part will balloon out. We know the static parts, the limits and just how far we can squeeze in all cases–if we do our work ahead of time. And we always do.
So there you have it. You’re ready for the fun part, landing the jet. Enjoy.
Coming on Wednesday:
What’s it like to ride 4 million pounds of explosives into space?
My one on one interview with astronaut Mike Mullane.