How high is this plane?

[scr4]

@scr4

This article links to the same video and says it’s from a Canon PowerShot SX50 HS with a 24-1200mm equilvalent lens. A 1200mm lens has a view angle of 1.15 x 1.72 degrees. This plane appears to subtend about 2/3 of the width of the frame. Assuming it shows a 200-ft long plane viewed directly from the side, that would imply the plane was about 10,000 ft (1.9 miles) away.

That’s the distance from the camera to the plane. The altitude is harder to estimate, but assuming the plane was about 45 degrees elevation as seen from the camera, the altitude would be about 7100 ft.

I need to correct myself. It turns out the SX50 has a 24-1200 lens and a 4x digital zoom. Combine both and you get 200x zoom. So at the highest zoom, the equivalent focal length is not 1200mm, but 4800mm. So my numbers above need to be multiplied by 4. The plane is about 7.6 miles away, at an altitude of 28,000 ft or so.

[Duckster]

@scr4

I need to correct myself. It turns out the SX50 has a 24-1200 lens and a 4x digital zoom. Combine both and you get 200x zoom. So at the highest zoom, the equivalent focal length is not 1200mm, but 4800mm. So my numbers above need to be multiplied by 4. The plane is about 7.6 miles away, at an altitude of 28,000 ft or so.

Nice correction.

14,000.

[scr4]

@Duckster

Nice correction.

14,000.

Could you please elaborate?

[Colophon]

@engineer_comp_geek

It looks like the plane goes from an angle of about 20 deg or so off of the nose to about 20 deg or so off of the tail over the 30-ish seconds of video. That looks like an MD-11 which according to The Google has a cruising speed of roughly 550 mph (other similar jets will have about the same cruising speed if my plane identification is a bit off). If I did my math right, then that’s about 9 miles per minute and over 30 seconds it would have gone roughly 4 1/2 miles. With those angles, that puts it at roughly 2 1/2 miles away from the camera. The plane isn’t directly overhead, so it’s at an altitude of maybe 2 miles or so.

This assumes that the plane is at full cruising speed. If it’s going slower, like maybe only 300 mph, then it’s altitude will be lower. At that altitude it might be taking off or landing, which would again explain the slower speed.

So my best guess is it’s at an altitude of somewhere between about 6,000 and 10,000 feet, depending on how fast it’s going.

It’s nowhere near the typical jet altitude of 30,000 to 40,000 feet.

No way is that plane as low as 6 - 10k feet. I see planes at that kind of altitude all the time over my house on the approach to Heathrow and they look BIG even to the naked eye.

FWIW this is a picture of a plane at 38,000ft taken with a Nikon P900 (83x optical zoom). I’m strongly considering buying one of those.

[LSLGuy]

@Colophon

…
FWIW this is a picture of a plane at 38,000ft taken with a Nikon P900 (83x optical zoom). I’m strongly considering buying one of those.

You’re right. Those are nice planes. I’m sure you’ll enjoy having one.

[engineer_comp_geek]

@Colophon

No way is that plane as low as 6 - 10k feet. I see planes at that kind of altitude all the time over my house on the approach to Heathrow and they look BIG even to the naked eye.

Well, I’m pretty confident about my math. I’m not so confident that I eyeballed the angle of the plane correctly, and if the plane were slowly banking away from the camera at the time it would be even more off. Since all of the other evidence indicates that it’s much higher, I’m inclined to believe that I pretty well whiffed it with my guess.

[Colophon]

@LSLGuy

You’re right. Those are nice planes. I’m sure you’ll enjoy having one.

It’s the parking charges that kill you.

[Bookkeeper]

@Colophon

It’s the parking charges that kill you.

Nah, you just need a bigger garage.

[Robot_Arm]

@LSLGuy

Not too many MD-11s were sold. The three-engine three-pilot era was ending, at least for passenger service. They did make good freighters though.

While we’re on the subject, Douglas and Lockheed were both considering three-engine, wide-body airliners at the same time. It costs billions to design and start building an airliner, and the companies that do it will have to have some number of confirmed orders before they commit to the project. Douglas and Lockheed were trying to line up customers at the same time. Douglas got American Airlines and United and started building the DC-10; Lockheed got TWA and Eastern and started building the L-1011. There might have been enough of a market for one plane in that class to recoup its development costs, but not two. It was pretty much the last hurrah for both companies in terms of airliners.

I was checking Wikipedia for this post; I knew the L-1011 wasn’t a success, but I was surprised just how few of them were built. I never did fly on one.

[LSLGuy]

Delta also flew L-1011s. As did several European carriers.

The Lockheed was the better aircraft. But they critically misundersestimated the market for a larger stretched model. The DC-10 was able to grow. The Lockheed not nearly so much. That shortened the production lifespan a bunch on the end. The 2-year delay for the Lockheed’s Rolls Royce engines also shortened the production run at the start. And drove several initial Lockheed customers over to Douglas before taking their first delivery. The delay also made the Lockheed a contemporary of the much cheaper to operate 767 rather than being a predecessor class with a decent and growing installed base as the DC-10 was.

Funny, but the 707 & DC-8 had the same growth issue. For various technical reasons the ability to stretch the 707 was far more limited than was the DC-8. Which is a big piece of why even though the 707 was a great success, the DC-8 lived on many years after the last commercial 707 was gone.

One side effect of Lockheed’s RR engine debacle was that henceforth Boeing would not offer an aircraft with only one manufacturer of engine; pretty much everything since then has two or three choices of engine manufacturer. Airbus picked up the same lesson. The 737 remains the sole exception in production today.

That lesson may be fading as it seems the future 777-8X, & -9X will be offered with only one engine type. Ditto the A350 just starting high volume production. The degree of airframe / engine interaction and optimization these days makes it increasingly non-performant to offer multiple engines. Not to mention the challenge of trying to get the engine manufacturers to invest capital in a new engine project with only 1/2 or 1/3 of the market as a realistic goal.

[Robot_Arm]

@LSLGuy

Delta also flew L-1011s. As did several European carriers.

Pan Am flew them as well, but I only saw Eastern and TWA when scanning the Wikipedia entry. I figured those were the launch customers and the rest came later.

Doing a bit of googling and it’s surprising. Looks like Northwest only had DC-10s and TWA only L-1011s, but the rest of the U.S. majors operated both at one time or another. Some of them may have been acquired when buying out a competitor.

It’s interesting that you say the L-1011 was the better plane. Is there a general consensus among pilots about which planes are better than others?