(Besides giving all of your passengers a heart attack, I mean, and getting banned from flying.)
All hypothetical, of course: How low under the rim could you fly? For what maximum distance, given the terrain? Would updrafts or other atmospheric peculiarities present themselves as a problem? Does lack of wingtip clearance impact aerodynamic stability? Are there any sections of the canyon that turn too sharply for safe maneuvering? (Safe, of course, being a relative term, assuming one is nutty enough to do this in the first place.)
I’m not suggesting anybody actually do this. I was reading one of my Calvin and Hobbes books, see, and, well, I just got to wondering what would actually happen if somebody did this.
This reminds me of a publicity stunt by a Sydney radio station in the 1970s…
Promoted heavily for days or weeks, it was a competition in which the first prize was “a ride on a jumbo under the Sydney Harbour Bridge”.
You’re probably way ahead of me here. Yes, the radio announcers were very careful not to use the words “fly” or “plane” in their promotions of the competition, and sure enough, when the day came, the “jumbo” was an elephant standing rather goofily on a barge, ready to be towed under the bridge.
All very well of course, except the woman who’d won the “jumbo ride” had never been on a plane before, was incredibly excited, and failed to see the funny side at all. I think she was close to tears. The station felt guilty and gave her a couple of plane tickets anyway.
Only in 1970’s Australia.
Anyway, I have often wondered if it’d be possible to safely fly a Boeing 747 under the Sydney Harbour Bridge. I think the height from the water to the roadway deck, IIRC is 57m.
When I visited Meteor Crater this last summer, they told us a story about a plane that flew down in it one time. The plane was unable to fly out because IIRC the wind was flowing right over the top of the crater and it stopped the plane from leaving. I wonder if something of the same thing wouldn’t hppen to a large plane in the Grand Canyon.
I imaginge that if you were in the canyon that it would be really loud once the plane went over head especially if the plane and low and the wall of the canyon were close.
I think the Grand Canyon averages a mile deep and five miles wide at the rim. So even half way down inside the canyon it’s still at the narrowest a mile wide. I’ll see if I can find a cite…
According to National Geographic the Grand Canyon is as wide as 18 miles at the rim. Of course at some point near river level the walls would close in enough to clip the wings. I think if the pilot were to fly 2000 feet above river level there would be plenty of room, and the plane would still be a 2000 or 3000 feet below the level of the rim.
An old F-16 simulator, Falcon 3 by Spectrum Holobyte, had a representation of some of the Grand Canyon. I believe it was fairly accurate. Portions of the canyon were easy to follow, and others were too tight for even a nimble plane like the F-16 to handle.
A 747 could dip briefly into some portions, but likely couldn’t make even the first bend it came to. That’s not what a passenger jetliner was defined for.
Zebra, there was still a little bit of the wreckage at the bottom. I believe this incident happened around 20 years ago, they just left some of the debris down there so that they could have that story to tell.
Now that I rethink this, I believe that the Grand Canyon would not hav ths effect on a plane. However, there may be some pretty strange winds that could wreak havoc on piloting a plane.
I’ve done a fair amount of low-level mountain flying. There are a number of precautions you need to take when flying below the level of the terrain. Specifically, you have to be aware of conditions which can create severe turbulence, and conditions which can create downdrafts on the lee side of a ridge. Thus, you approach all ridges at a 45 degree angle so you can turn away from them if you find yourself in a powerful downdraft.
Now, this is canyon flying in the Rocky Mountains of Canada, which is a damn sight tighter than the wide parts of the Grand Canyon. We’re talking about flying at 4500 ft with 14,000 ft peaks around you, and the Canyon walls often being no more than a mile or so wide. And large jets fly into airports nestled inside these canyons.
The problem with flying a 747 in the Grand Canyon really doesn’t have anything to do with manoevering or strange strange aerodynamic effects. The main problem would be the danger of wind shear. When a large jet loses energy, it take it a long time to gain that energy back. That’s why a Cessna 150 can fly through a wind shear that will bring down a 747.
So, the moral of the story is that you shouldn’t try it on a windy day, and if you do, keep your speed up so you can climb out of trouble. Given that, I’ll fly a 747 through the wider parts of the Canyon, no problem. Just don’t ask me to turn and bank all over the place - a 747 at cruise speed has a very wide turning radius.
As a related aside, it can be just as dangerous to fly over the Grand Canyon as in it; there’s been a number of accidents involving sightseeing planes and helicopters over the years.
The most notable incident, though, when a TWA and a United flight collided over the canyon in 1956, sending both planes tumbling into its depths - with 128 fatalities, it was for a while the deadliest crash in American aviation history. IIRC, much of the wreckage of the two planes is still down in there, 45 years later.
Legally speaking, from FAR 91.119: “no person may operate an aircraft below the following altitudes: (a) Anywhere: an altitdue allowing, if a power unit fails, an emergency landing without undue hazard to persons or property on the surface.” So, while this is a judgement call by the pilot, I doubt the average pilot of a 747 would feel comfortable making an emergency landing if his engines quit while he’s 500 feet or less above the floor of the Canyon. Hypothetically speaking, I’d say you could fly as low as you want. The part of Canyon I’ve seen was incredibly wide, and pretty long. All you’d need is to clear any hazards near the ground, and enough velocity and/or altitude to climb out before smacking into the first turn of the Canyon ahead of you.
**For what maximum distance, given the terrain? **
See last question.
Would updrafts or other atmospheric peculiarities present themselves as a problem?
Of course. I’d think in this case you’d be concerned more with downdrafts than updrafts, though. You could always do it at night to avoid the most active drafts, but then you’d give yourself other problems…
Does lack of wingtip clearance impact aerodynamic stability?
Once you get to within a wingspan of the ground, you get into what’s called ground effect, and this will affect wing aerodynamics. I’ve never heard of any distance from the wingtips, though (IANAPhysicist). So my guess is no. But I’d also guess a lack of wingtip clearance would have a rather large effect on pilot pucker factor.
**Are there any sections of the canyon that turn too sharply for safe maneuvering? **
I’m no Canyon expert (or a 747 expert, for that matter), but I really doubt there’re any turns that are gentle enough to accomodate a 747.
