Thursday, October 16, 2014

Migratory Birds

I learned to use a GPS receiver for air navigation when I was working in the north. Many of the airplanes in the fleet had three line text GPS units. Some had none, but even that nascent technology was so useful, compared to the NDB airways and map-compass-watch navigation they supplemented, that captains spent their own money on handheld units, for the days we were assigned airplanes that lacked the magic box. Airports, radio navigation aids and other named fixes are few and far between in the far north. Given a full load of passengers and cargo and fuel to max gross weight, there wouldn't usually be more than four or five airports within range. It was pretty much guaranteed that when we selected the we selected the "nearest" function, the intended destination would be on the first page. That was the quickest way to select waypoints: no tedious dialing in three- to five-letter identifiers letter-by-letter. Back then we just hit NRST (or rather, I don't remember exactly how, selected it from an obscure user interface), and selected the one we wanted from the list.

Of course this technique doesn't work down south, where there may be hundreds of little municipal and farm airports within an hour's range. Now I'm resigned to dialing in my waypoints, one letter at a time, into the much newer, but still not state of the art GPS unit. But every once in a while the way I learned first re-emerges and I hit the NRST button, to be bewildered by a list of unfamiliar identifiers. Today 'm flying in northern Alberta, not much in the way of towns around here, just a big whack of restricted military airspace. I'm given a reroute via a five-letter fix, still called an "intersection" because once upon a time each was defined by the intersection of two airways. Some still can be located that way, but many are simply convenient lat-long points in space. I always wonder why there are so many of them in close vicinity of LETRM. I think it may have something to do with routing aircraft around the military airspace. Usually they aren't that dense outside the terminal airspace of a busy cluster of airports. Or maybe I just remember better not to do that nearest thing when I'm in an urban area.

Approaching destination I hear the controller talking to a pilot who says he's on a migratory bird tracking flight. I'd never heard of such a thing. The controller says it's great to watch the birds migrating on the radar. Wow, I did not know that either. Birds so thick that they paint primary surveillance radar are a force to be reckoned with. The controller offers to send the pilot a tape, and if I weren't busy getting set up for the approach, I might have asked "me too!"

Here's a composite radar picture of bird migration in the US (see the notes on YouTube for an explanation of what you are looking at). I couldn't find a recording of what it looks like on a local level. How many birds does it take to show up, and can you see the V shape of the skein?

I switched to tower frequency and landed in a challenging crosswind, fighting winds twenty to thirty degrees off the runway and twenty-two knots gusting up to thirty-five, all the way down to the runway. I touch down centred and straight and straight, with one little bounce, but I laugh and point out that they were both smooth landings.


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Anonymous said...

Wow. You once said that birds were found to put telephone wire into their nests, in order to monitor the ATIS. How do they "ident", once airborne? Will it remain a mystery?

Unknown said...

At least migrating birds and so confusing to radars watching the air.
They confuse the hell out of naval surface watching radars, though. The blip size, movement speed and altitude are much more reasonable for a fast ship than a slow aircraft. I spent the better part of three years chasing bird shadows in the sea.

Unknown said...

Easy, they squawk.

Unknown said...

birds Ident by squawking, duh. ;)