Operational Limitations for 767
Please Note: The limitations data contained on these pages is applicable only to the Boeing 767-300 with Rolls Royce RB211 engines, unless otherwise stated.
MAXIMUM SPEEDS
Bird Impact Protection
From Sea Level to 8,000ft restrict airspeed to 313 kts* for Bird Impact Protection. Above 8,000ft, observe Vmo / Mmo pointer and overspeed warning.
*313 kts = 360 mph
Pentagon & Boeing 757 Ground Effect
In the aftermath of 9/11, I have heard many claims that a 757 could not possible have hit the Pentagon because the plane cannot fly so low to the ground at speeds of 500 mph or more. The primary reason given is that ground effect prevents this from happening. Is there any truth to this claim?
- question from Eric
I am researching Flight 77 hitting the Pentagon. The aircraft was a Boeing 757-200 traveling 345 mph according to the flight data recorder. Because of damage to light poles about 1500 feet from the building, the leading edge of the wing was about 15-18 feet off the ground at this location. The impact damage at the building is contained below the slab of the second floor, which is 14 feet high. Nothing hit the lawn prior to the building facade. How would ground effect have been overcome for this scenario?
- question from Russell Pickering
Your article on ground effect says that it comes into play at a height equivalent to the wingspan of the aircraft, or about 125 ft for a 757. If a 757 tried to fly at low altitude at 500 mph, wouldn't ground effect force it up to at least 125 ft? And if the pilot tried to force the nose down at that speed, wouldn't the aircraft become unstable? I don't think any pilot could control an aircraft like that and hit the Pentagon. No 757 could fly like that, especially the terrorist supposedly flying Flight 11 who was an unskilled amateur pilot yet magically flew with total perfection.
- question from S. R.
We have previously explored one of the most common questions about the attack on the Pentagon on 11 September 2001 in an article about engine wreckage photographed at the site. Another popular question raised by many who doubt the official story of what happened that day concerns the aerodynamic phenomenon known as ground effect.
Ground effect primarily affects the aerodynamic behavior of a conventional fixed-wing aircraft during landing. In order to understand what ground effect is and how it works, one must first understand the concept of trailing or tip vortices. A vortex is an energetic swirling mass of air or water like a tornado or whirlpool. All aircraft, and birds for that matter, generate vortices off their wingtips. These vortices form because of the difference in pressure that exists between the upper and lower surfaces of the wing.
Aerospaceweb.org | Ask Us - Pentagon & Boeing 757 Ground Effect