Low flying jets. How is this not dangerous?

I didn’t check any of the links above, but hopefully one of them is to airliners.net. Excellent site for airplane pics.

Haven’t been to St. Maarten, but I recall that planes came in pretty low over the road that went round the east side of the old Stapleton airport in Denver.

I also recall driving past a military airbase in Northern Scotland (Kinloss?)where a public road passed so close to the end of the runway that the RAF had installed traffic lights that were activated when a plane approached.

I’ve seen that elsewhere, too…possibly on Anglesea, in Wales?

…and is listed in the Highway Code: " At level crossings, lifting bridges, airfields, fire stations, etc"

It would take a hell of a wind to pick someone up. People can stand around fairly comfortably in 50kt winds (well, it’d be blustery and they’d have to lean into it, but there’d be no danger of being picked up.) These airliners are pretty much at idle power so there’s no great wind coming from the engines, the only other place for it to come from is off the trailing edge of the wing, and although the wing does accelerate air over the top surface and down from the trailing edge, it won’t generate anything like the airflow required to concern anyone standing underneath.

As for the altitude of the aircraft, the standard height of an aircraft as it crosses the threshold of a runway is 50’, so these are probably around 70-100’ above the ground in the photos.

Right. Specially with the pics of the 747s, it looks like they are about to take out the highway divider withtheir mains, just because those are some BIG mothers and the sense of perspective gets distorted.

Also, you land slower than you take off and it would seem to me that at such a point in the approach the formation of large wake vortices would be broken up by, well, the ground itself.

Judging from the whole sign at the bar there must be something to look at there every hour of every day, but that’s not really relevant to the question :wink:

Was in St Maarten in 91. Stood on THAT beach, yepper, they are that low. Arrived on a 45’ Alden Sloop and left on a DC-10. That was some short lookin runway for a plane that big.

Oh, standing behind a big jet aircraft that is at takeoff power or full power is a bit wilder than one that is landing at flight idle. If a pilot had initiated an ‘go around’ or was aborting an landing and had spooled up top full power and was rotating just as he passed over you as low as they do at St Maarten, well, then the people and sand just might get blown around more. :wink:

Airline pilot here. I’ve never been to SXM, but here’s some thoughts …

This photo http://www.jetphotos.net/viewphoto.php?id=6 is probably the best on the Net for measuring the situation. The official airport map is also available http://www.jetphotos.net/airports/tncm/taxi.gif, but the copy quality is not good enough to see the road and beach, which is acurately depicted on the actual chart

The airplane (767-300) is 180’ 3" long. Based on that, I measure the height of the landing gear at roughly 60 feet above the road. A typical descent angle is 300 ft/nautical mile, or roughly 1ft vertical / 20ft horizontal. So the airplane is about 60*20 = 1200 feet from touchdown.

As a rule of thumb, for large airplanes like that we aim to have gear impact at about 1000’ down the runway. (You may read things about widebody aimpoints being 1500’ down, but relates to where you’re aiming your face to impact, not your gear.) As we generally do a flare manuever at the end, the actual gear touchdown point ends up 1500-ish feet down the runway.

The implication is the actual runway threshhold is just 200 feet ahead of the nose of the aircraft, about 1 aircraft length. The pavement you see under the nose with the white chevron painted on it is called overrun; it’s no stronger than a road and won’t hold an airplane’s weight. It’s just there to provide a smooth debris-free surface so takeoffs don’t blow junk around, and in the event of an overrun off the other end, there’s nothing to run into as you sink into the pavement.

Overruns are typically 1000’ long, but at SXM they are either 200’ or 255’ long depending on which end of the airport we’re talking about.
Sitting on that beach would be in no way dangerous, except to your hearing. The overflight noise is really pretty cool, first a loud roar and then an eery whistling sound as the wake vortices swirl over you. The roar is loud, but not deafening. The wake will ruffle your hair, but that’s about it. Typical Caribbean shore breezes are similarly powerful.
At takeoff power, the jetblast from a big jet is real significant out to maybe 200’. Beyond that it’s still windy, but not to the point of throwing pickup trucks around. They may also have restrictions on how much power can be applied how close to the beginning of the runway. The falloff in exhaust blast velocity & density is almost exponential, so a little more distance buys a lot of reduction.
Years ago at Las Vegas you could get to a similar spot relative to runway 01R; the difference was there was no road outside the fence, just desert, and the overrun was IIRC 500 ft, not 200. Due to prevailing winds, that runway was rarely used for takeoffs, but when it was, it was a treat to go out there.

If you (me actually) went right up to the fence and aligned yourself right behind an engine of whoever was taking off, 727s & 737s being the typical types, you had to hook your fingers into the cyclone fence and a few times I got my feet kicked out from under me, so I was flying a la Superman hanging onto the fence. Great fun, immersed in a very warm, very keroseney blast of hurricane winds for a few seconds. I lost a fine pair of GI sunglasses that got swept off my face that way. Searched downwind for 100 yards and never did find 'em.

To see the power of jet blast in close, check out this video http://www.aviationexplorer.com/747_engine_blast.htm

LSL guy, that is really an amazing video. It is true Jet blast is loud and powerful.

Is it just me, or does it look like one of the landing gears isn’t quite all the way down?

Actually, the phenomenon with long lenses is called telephoto distortion. Long lenses tend to ‘squeeze’ the background and the foreground together so that there appears to be less distance between them.

As for the wind: The dangerous part (at least to light aircraft pilots) is the wingtip vortex. These are like horizontal tornadoes that sink and spread outward when the wings are developing lift. Wingtip vortices can upset small aircraft that run into them, which can be dangerous at low altitudes such as experienced when landing. Can they lift a person up and blow them away? I don’t know. Someone noted that a person can stand in a 50 knot wind (and I have done); but I don’t know what would happen if they were in a sudden gust.

Real Video clip of an AF747 taking off St marteen and jetblasting people on the beach behind it:


The main landing gear trucks or bogies on the 747 hang rear wheels down, this is probably what makes them look like they aren’t down properly.