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| Title: | Collision with localizer on takeoff, United Airlines Flight 663, Boeing 727-222, N7647U, Denver, Colorado, May 31, 1984 |
| Micro summary: | This Boeing 727-222 struck the localizer antenna on takeoff, resulting in pressurization problems. |
| Event Time: | 1984-05-31 at 1334 MDT |
| File Name: | 1984-05-31-US.pdf |
| Publishing Agency: | National Transportation Safety Board (NTSB) |
| Publishing Country: | USA |
| Report number: | NTSB-AAR-85-05 |
| Pages: | 78 |
| Site of event: | Takeoff RWY 35L |
| Departure: | Denver Stapleton International Airport, Denver, Colorado, USA |
| Destination: | Stapleton (Diversion) |
| Airplane Type(s): | Boeing 727-222 |
| Flight Phase: | Takeoff |
| Registration(s): | N7647U |
| Operator(s): | United Airlines |
| Type of flight: | Revenue |
| Occupants: | 105 |
| Fatalities: | 0 |
| Serious Injuries: | 0 |
| Minor/Non-Injured: | 105 |
| Other Injuries: | 0 |
| Executive Summary: | On May 31, 1984, at 1334 MDT, United Airlines Flight 663, a Boeing 727, struck the localizer antenna 1,074 feet beyond the departure end of runway 35L during takeoff at Stapleton International Airport, Denver, Colorado. The flight was en route to Las Vegas, Nevada, with 98 passengers and 7 crewmembers aboard. The flightcrew said they were not aware that the airplane had struck the antenna. When they were not able to pressurize the airplane after takeoff, the captain decided to return and land at Stapleton. The approach and landing on runway 26L was uneventful. There were no injuries, but the airplane sustained substantial airframe damage when it struck the antenna. The National Transportation Safety Board determines that the probable cause of the accident was an encounter with severe wind shear from microburst activity following the captain's decision to take off under meteorological conditions conducive to severe wind shear. Factors which influenced his decisionmaking include: (1) the limitations of the low level wind shear alert system to provide readily usable shear information, and the incorrect terminology used by the controller in reporting this information; (2) the captain's erroneous assessment of a wind shear report from a turboprop airplane and the fact that he did not receive a wind shear report from a departing airplane similar to his airplane because of congestion on the air traffic control radio frequency; (3) successful takeoffs made by several other air carrier airplanes in sequence; and (4) the captain's previous experience operating successfully at Denver under wind shear conditions. |
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