Wednesday, March 09, 2011
By request, here's a video of our ILS into Boston this morning. select 720p and embiggen it to fullscreen for maximum fun. The weather was fine - 2,900' overcast with decent visibility underneath - but a gusty crosswind from the right kept it from being boring. This is runway 04R. They were using runway 09 to depart airplanes, so from time to time you might see other airplanes blasting off across our runway from left to right.
Kitsch hand-flew the approach, I played on the radios.
For those of you who care - there are 4 lights just to the left of the runway, called PAPI lights. They are used when flying the visual approach - if you are on the correct glide path, two of the lights will appear white, and 2 of them will appear red. If you see more white lights, you are a little high, and if you see more red lights, you are a little low. An ILS approach may have a slightly different touchdown point on the runway, and the PAPI lights may indicate a different picture than the instruments on board the airplane - for example, on runway 05 going into Toronto, the PAPI lights will show 3 or 4 red lights while the Instrument Landing System shows us as being on the glidepath. If we are flying the visual approach, we'll fly the PAPI lights, and if we are flying the ILS we'll fly the electronic glideslope indication in our airplane.
A person in the comments section asked about the construction cranes on an island just before we landed at Boston - they are actually loading cranes used to put shipping containers onto ocean-going vessels. The person expressed surprise that they are allowed to be placed so close to the runway. As far as the cranes - they are maybe 50 - 70' above the water, and maybe 1 1/2 miles from the threshold - you can hear the radar altimeter lady say "500" as we are passing them, so she's telling us we are 500' above the ground at the time. If you are low enough to hit the cranes at 1 1/2 miles back, you have bigger problems than the cranes, like hitting the water. If you stay on the correct slope, you will have plenty of vertical clearance over them - at a 3 degree glideslope, you will be 300' above the runway for every mile back you are.
If we are taking off, we are assured of vertical clearance over any obstacles in our departure path as long as we adhere to the appropriate departure procedures, which is normally a climb gradient of 200' per horizontal nautical mile. In this case, the required climb gradient on runway 22L (the reverse heading of the runway we landed on) is "standard if tower reports no tall vessels in the departure area". However, on runway 22R, which is just a couple of hundred feet away from it (and in fact a bit closer to the loading cranes), you need a higher climb gradient than normal to assure obstacle clearance. In that case, you need to climb at 320' per nautical mile until you are 600' above sea level. If we were departing on that runway and the weather was bad, we'd consult our airplane charts to make sure that at our takeoff weight we could climb at that climb gradient even if we lost an engine right as we took off.
That actually would be a good subject for a pilot-geek-post - the things we do in low visibility conditions to assure obstacle clearance. If the weather is good, we can just turn to avoid things like cranes and buildings and mountains, but when we can't see outside due to fog etc, we follow a whole complicated set of rules, and the math gets a lot more in-depth (we have an app for that :p). I will start on a post like that some time in the near future.
Anyway, this morning was a nice, routine flight. Now off to a yummy seafood place for lunch! :)