Autothrottles

By lex, on January 2nd, 2012

Courtesy of SpazSinbad, a Youtube video that almost – almost – makes the drudgery involved in preparing for sea during field carrier landing practice look interesting.

It’s the music, mainly. Can’t think of anything else to explain it.

LSOs these days, with actual shacks to sit in. Away from the bugs and the heat.

Makes them soft, I should think.

There are three crucial factors the pilot must control in a carrier landing approach: glideslope, lineup and angle-of-attack. The ship may heave, pitch and roll, but that is only of incidental value. Entertainment by terror if you will, especially at night.

“Quote Thoreau and simplify”, said Michael Stipe, and fortunately for your host – a simple man if ever there was one – McDonnell Douglas engineers had the wisdom and foresight to emplace the Approach Power Compensation system aboard his steed. The APC (or autothrottles) essentially tied the aircraft power setting and angle of attack to the stick pitch position. In a manual approach, the proper response to being a little high, for example, would be to ease off a percent or two of thrust using your left hand on the throttles, and then carefully bunt the nose over to capture and maintain the correct angle-of-attack. If you didn’t bunt the nose, the aircraft would eventually seek the trimmed AOA, but not before flashing a slow, going further high, and causing paddles heartburn and distress. Which in turn might cause you to get waived off, adversely affecting your landing grade performance, self-esteem and special snowflake status.

Coming back down on glideslope, the whole thing had to be repeated again: Correction, counter-correction, re-counter-correction.

But the APC allowed you to press a button on the throttle and, hey presto: All of that angle-of-attack stuff went away (assuming you were properly trimmed at APC engagement). Rather than manually move the throttles, you merely made the nose up or nose down correction required by your glideslope deviation and the throttles would creep up or back to maintain the proper speed. It basically reduced your workload from meatball, lineup, AoA to “meatball, lineup”. An efficiency of 33%!

When you came aboard during CQ operations or at night (so-called “zip-lip” operations were standard during daylight, non-CQ operations), the auto flyer was required to report the fact that he was in fact flying, well: Auto. Due to some residual fear, uncertainty and doubt in the LSO community, which was ever a superstitious lot what with their pickles, worry beads and chicken’s feet necklaces. I say that having been a member of the fraternity. They gave me a hat. I have the hat to this day. I have the hat.

So on your ball call it’d be, “404, Hornet ball, 4.2, auto” and the reply would very often be, “Roger ball, auto.”

I was very fond of autothrottles, they’d been very, very good to me over the years. Treated it as summat of an emergency when they weren’t operative. If only for the lack of familiarity that was in it, killing snakes in the cockpit with both stick and throttles. So it came to pass one day during fleet CQ that the ship had contrived to find herself in gusty conditions, with winds over the deck in excess of 35 knots. The senior LSO on station called on the Tower frequency, “99 Slapshot, winds are 35 knots, four-degree glideslope, all Hornets go manual.”

Which it was good to know that the winds were 35+ knots, for that would affect where you chose to turn from downwind to final – delay too long and you’d be deep in the groove and sent around to try it again – but the four-degree glideslope was one of those, “eh” statements. It was supposed to mean something to pilots, but I was a pilot for many years and I never quite figured out what. You fly the ball to touchdown, and glideslope be damned. As for that last bit about “going manual”, that must have gone into my bad ear, for I entirely missed it.

My turn to come around and have a look at the deck eventually arrived, and I broke to downwind, configured the jet for landing and selected APC. Rolling out on final, I reported, “401, Hornet ball, 5.6″, primly omitting the fact that the APC was in fact engaged. For the LSO, she seemed busy. And I didn’t want to overload her. With too much data.

She had her reasons, not to mention her fears and superstitions, for asking the pilots to go manual. It was a little higher than normal workload in gusty conditions, and the APC could struggle to keep up with the larger stick deflections. I just felt like I knew my own capabilities and limitations better than that LSO, who was in any case rather bossy and not someone I would ordinarily invite into my cockpit, especially when it was getting cramped and crowded.

So when the debrief time came along, she looked at me with a suspicious glare, and asked whether I was in fact flying auto, at all?

“Who would fly auto in these conditions?” I replied sadly.

Thus mollified, she read me my grades (quite good), theorizing that I had so long flown auto that even my manual corrections had the appearance of being made in autothrottles.

And who was I to argue with the LSO?

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