Saturday, July 14, 2007

RTF Days 4 and 5: Compression, Slop, and Departures

Today's Lessons
  • Speed Control
  • Vectoring
  • Departures
  • Block Test 1
The past few days have been half-lecture and half-simulation part task. The format we follow usually sees us doing a lecture on a particular subject (say, Speed Control) which is followed by a simulation where we put the theory into practice on a limited basis. For instance, on the vectoring simulation, you only do vectoring and are not allowed to adjust speed or altitude. In short, these part tasks build skill in particular areas, giving you a foundation that you can apply later on in more complex scenarios.

Speed Control

This is pretty straightforward overall, with a few red flags thrown in for fun. To describe it overall, speed management is how you maintain your separation in your pattern and is one of the methods you use for opening holes and establishing your sequence.
  • Anticipate: You need to take into account that airplanes do not slow down immediately and cannot descend below 10,000 feet if they're doing over 250 knots. For this reason, you really need to understand what your traffic needs to do before it can comply with your altitude restrictions.

    Example: Let's say you've got a 737 on your downwind leg, abeam Academy airport at 10,000 feet doing 350 knots. He's only four miles behind a Lear that's descending to 4,000 and is at 210 knots. You of course need 1000 feet or 3 miles separation. You tell the 737 "AAL237, reduce speed to one-niner-zero, then descend and maintain 4,000". The 737 has 140 knots on the Lear. By the time 737 complies with the speed reduction, he may be inside the 3 mile bubble around your Lear. A better thing to have done would have been to issue the speed restriction when the 737 was maybe six miles behind the Lear, which gives you a little wiggle room. Once they're down to similar speed, you can then issue smaller speed increases/reductions to tighten things up.
  • Compression: This ties in with anticipation. When you've got several aircraft lined up for the final, just keep in mind the following: the second that first airplane crosses the final approach fix, the flaps, gear, and slats will come out, the tray tables and seats will be in upright positions, and he will begin to bleed off speed like crazy as he slows to his approach speed. If you've got your airplanes exactly 3 miles apart, when that first one slams on the brakes the rest are going to "rear end" him (and eventually each other), and you will have a dangerous "accordion effect" with your traffic.

    You need to maintain that 3 miles. For this reason, you need to build yourself in a 1 mile cushion to anticipate for the compression that naturally occurs around the final approach fix. So, instead of keeping that 737 three miles behind that Lear, give him four miles and a similar airspeed. That way you're protected.
  • Keep 'Em High Program: Smoke 'em if you got 'em. Departing Turbojets and Turboprops like speed, and to get that speed they need to be climbed up high. For arriving jets/tprops, you should keep them as high as possible until it's a requirement to descend them. Think about it: the faster they get where they're going, the less time you have to deal with them. If you take them or keep them at 10,000 and up, there's no speed restriction. The Boeings can go 350 knots, the T-38's can zoom along at 500, and everyone's happy.

    Example: That 737 mentioned above probably checked in at 10,000 feet around 30 miles out at 350 knots. He's got a long way to go, and if you descend him he's going to have to pull back on that throttle and chunk nearly a third of his airspeed off. So, instead, you just keep him high, maneuver him into your pattern at 10,000 feet, and then you drop him and slow him.
  • Aircraft Performance: If you try to tell a Beech Bonanza to "Increase speed to two-five-zero", you're in for some disappointment. :) Just know your aircraft types and what they're capable of. There's a few here in the sims that were not in the Initial Tower course, such as:
    • ATR-42 (AT44)
    • Beechjet 400 (BE40)
    • C-130 (C130)
    • T-38 (T38)
    • Twin Comanche (PA30)
    • T-37 (T37)

A vector, by definition, is "a heading issued to an aircraft to provide navigational guidance by radar". Once again, understanding aircraft performance is key to doing this correctly. If you tell an F-16, a 747, and a Cessna 182 to turn right 90 degrees, you're going to get three vastly different radar tracks as they make their turns at varying speeds.

The distance an aircraft will travel before it fully turns on to its assigned heading is called "slopover" or just "slop". You need to account for this, in particular when you're working your pattern. A quick formula they gave us to work with was this: Speed / 100 = Miles of "slop".

So let's say we've got our 737, traveling at 200 knots on a heading of 180. We then issue him a heading of 270. So, using our formula, we calculate 200 knots / 100 = 2 miles of "slop". We can then predict that the aircraft will travel 2 miles further south during its turn before lining up on a heading of 270.

The lesson covered methods and phraseology such as:
  • Assigning headings: "Fly heading 220" "Turn right heading 190"
  • Reasons for vectoring: "Vector to final approach course" "Vector for spacing" Etc.
  • Incremental headings: "Turn twenty degrees right"
  • No gyro vectors: "This will be a no-gyro vector. Turn right." "Stop turn."
  • Restrictions: MVAs, VFRs, etc.
The part task simulation for this consisted of a "maze" through which we had to navigate various aircraft. Each aircraft has letters in its scratchpad, which tell you which departure gate you need to get it to ("AAA", "BBB", "CCC", etc.). Thrown into the mix was also one aircraft that lost its directional gyro, so you had to baby it through by giving it no gyro vectors.

Here's a shot of the maze. I blurred out the AC ID's on purpose; I don't want anyone to say I was giving out answers to this. This also shows you the STARS interface.


We basically went over the LOA's and procedures for each airport in our airspace and what we can expect as far as altitudes, headings, and authority. Each airport has different procedures and you need to know the phraseology for each intimately.

Subject matter included:
  • Initial climbouts for each airport (5000 for AAC, 4000 for JKE, 3000 for the satellites)
  • Initial turns
    • AAC: No turns below 3000 feet for noise-abatement aircraft (jets, turboprops)
    • JKE: Below 3000 feet, turns up to 90 degrees are permitted for all aircraft
    • Satellites: No turns until aircraft enters controlled airspace and is above MVA (2100)
  • Rolling calls for JKE
  • Release procedures for satellite airports
    • For James, the release request comes in from McAlester FSS (pilot calls in via telephone)
    • For Bartles, AAC Approach is reachable from the airplane on the ground, so the pilot will contact you directly.
Block Test 1

This was in the same computer-based format we used over in Initial Tower training. Prior to the test, we had an "interesting" review session where the instructors pitted one side of the class against the other over 48 questions. It was setup in a "Who wants to be a Millionaire" -meets- "The Weakest Link" format. The questions are multiple choice, but if you miss an answer your team gets bumped down to 0 points if you're not past 10,000 points. Really silly, but it was more fun than normal test reviews.


forress said...

Thanks for blogging the RTF stuff.

I have a question, so tower class is 7 weeks and if you passed the PV, they send you to RTF for another 2 1/2 weeks. How come some are going to their facilities first but you are going straight to RTF school?

And do they tell you this the first day you report to OKC? I would imagine it'll mess up ppl's return plane ticket if they don't tell you ahead of time.

Wicked Penguin said...

I'll actually answer that in a blog post, since a lot of people are confused on the RTF thing.