Why do planes ascend so sharply during takeoff?

Ron Wagner:

I’m guessing you’re referring to the steep climbs of commercial airplanes that passengers experience. Clearly, you perceive them as steep, but 'steep' is subjective—what feels steep to one person might feel like a smooth ride to another.

I’LL SHOW YOU WHAT 'STEAP' REALLY MEANS

I was fortunate enough to receive taxpayer-funded pilot training through the U.S. Air Force, which included flying the Northrop T-38 Talon supersonic jet. When it debuted, it held the record for the fastest climb in the world and set the global time-to-climb record.

The specific jet that set that record had the tail number 10849. After making history, 849 was added to the regular training fleet at Webb AFB in Big Spring, Texas, where I trained as a pilot. The folks at Edwards AFB, where the record was set, had painted a list of the records on the jet's nose, but otherwise, it became just another member of the Webb fleet.

Eleven years later, I had the chance to fly 849. Unfortunately, at that time, smartphones didn’t exist, so I couldn’t snap a picture of the list of records on the nose with me in the cockpit—what a missed opportunity!

The records were measured in meters, with many listed, but the most memorable one was the climb to 9000 meters—that's 30,000 feet.

The climb record had to be measured from the moment the aircraft first rolled on the runway, through takeoff, gear up, and into the climb. The entire process—from a complete stop to 30,000 feet—took just 62 seconds... and here’s a photo from that day, capturing the jet like a fiery angel striving to return to heaven.

Now that’s what I would call a ‘sharp’ takeoff.

Commercial airliners don't typically take off at a steep angle.

BUT AIRLINERS DON’T STAY LOW FOR LONG

Jet aircraft perform most efficiently at higher altitudes. The most fuel-efficient path for any jet on a long flight would involve climbing as fast as possible to cruising altitude, leveling off, reducing power for cruising, and maintaining that altitude until the engines can be idled for a landing descent.

Due to air traffic and passenger comfort, commercial airliners don't follow the most efficient flight profile, but they come close.

And that's why it feels like jet airliners climb at a 'relatively steep' angle, but trust me, they are not 'steep.' That T-38, now that was a steep climb!

JUST TO CLARIFY

A few years after, the F-4 surpassed the T-38's record. I haven't kept up with the latest developments, but I distinctly remember in 1975 when the F-15 brought the 9000-meter record down to 48.8 seconds.

I just watched a video of an airliner taking off and noticed that it left the ground about 50 seconds after releasing the brakes and raised the gear approximately one minute after brake release.

To put it simply: From the moment the brakes are released, the F-15 can reach 30,000 feet in the time it takes a typical airliner to just lift its nose on the runway. Forty. Eight. Point. Eight. Seconds.

The F-15 has a thrust-to-weight ratio greater than one, meaning it can accelerate vertically, much like a ballistic rocket.

Now that, my friends, is what we call the true definition of 'steep.'

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