NTSB Factual Report

On September 9, 2002, at 2246 eastern daylight time, a Boeing 757-251, N534US, operated by Northwest Airlines as flight 170, was substantially damaged when it experienced a tail strike while landing at Baltimore-Washington International Airport (BWI), Baltimore, Maryland. There were no injuries to the 2 certificated pilots, 4 flight attendants, and 97 passengers. Visual meteorological conditions prevailed for the scheduled passenger flight that originated from Minneapolis/St. Paul International Airport (MSP), Minneapolis, Minnesota. The flight was conducted on an instrument flight rules (IFR) flight plan under 14 CFR Part 121.

The departure, en route, and initial approach phases were reported to be without incident.

According to the captain's statement, the flightcrew had briefed for a visual approach to runway 33L, and made a right turn to the runway. However, the airplane was aligned with runway 33R. The flightcrew was advised by the control tower of their runway alignment. The first officer called for a go-around; however, the captain had runway 33L in sight, and elected to maneuver the airplane to that runway for landing. The captain further stated:

"...The approach was flown inbound at what looking back was a low altitude. We crossed the threshold at about one dot low on glide slope. At this point, the co-pilot again suggested a go-around, but I had become fixated on landing the AC. I felt I was in a position to land, so I added power to return to the glide slope, but when I retarded the power to correct, I pulled off too much power and did not properly arrest the sink and we landed very firmly...."

According to the first officer's statement:

"...With calling for a go-around, I made no 1,000 inst. normal call. As we approached final, I believe the aural warnings ceased. We rolled out on final, on speed, but still a little low. I called 200' to touchdown and felt we were still low for a normal flare and touchdown, so I again called for a go-around. As we crossed the threshold, the captain retarded the throttles to idle, higher than usual for a normal landing. This resulted in a very firm landing...."

The airplane was taxied to the gate where the passengers deplaned through the jetway.

According to data from Northwest Airlines, the aft pressure bulkhead was buckled, and subsequently repaired with the addition of stiffeners. In addition, a portion of the lower aft fuselage skin was replaced.

According to data from the Federal Aviation Administration (FAA), runways 33L and 33R were separated by about 4,600 feet. The published airport elevation was 146 feet, and the published touchdown zone elevation (TDZE) for runway 33L was 129 feet. The published heading for runway 33L was 335 degrees magnetic.

Northwest Airlines supplied flight recorder data for the last 11 minutes of flight and subsequent ground operation. There was a data loss at the time of touchdown, and the pitch attitude and "g" load at touchdown were not available.

According to flight recorder data, about 50 seconds prior to touchdown, the airplane initially lined up on a heading near 335 degrees, at an altitude of about 500 feet above the touchdown zone elevation of runway 33L. The airplane then turned left and then right, while descending. The airplane lined up near a heading of 335 degrees about four seconds prior to touchdown, when according to the radar altimeter, the airplane was passing through about 50 feet above ground level (AGL).

The speedbrakes were extended when the pilot initiated the descent from 5,000 feet, and remained extended through the touchdown. When interviewed by Northwest Airlines safety personnel, the flight crew reported that they were not aware that the speedbrakes were still extended at touchdown.

The pitch attitude of the airplane 2 seconds prior to touchdown was 14.06 degrees nose up. At one second prior to touchdown, the pitch attitude was 11.25 degrees nose up. According to Northwest Airlines safety personnel, with the main landing gear struts compressed, the tail of a Boeing 757-251 would contact the runway at a pitch attitude of 10.5 degrees nose up.

On final approach, the airplane was flown below the glide slope for 1 minute, 47 seconds, and only passed above the glide slope, 1 second prior to touchdown.

According to Northwest Airlines, Flight Operations Manual (FOM), Section 9.2.2 Approach:

"A stabilized approach has the following criteria...the airplane is aligned with the intended landing runway prior to reaching a point 500 feet above the TDZE unless on a prescribed approach procedure.

According to the Northwest Airlines, FAA approved, Boeing 757, Aircraft Operating Manual (AOM):

"...When using speedbrakes the PF [pilot flying] should keep one hand on the speedbrake lever as a reminder to lower the speedbrakes when they are no longer required."

According to Northwest Airlines Boeing 757 Aircraft Operating Manual, the airplane was equipped with multiple caution and warning systems, including an aural caution for extension of the speed brakes, with the airplane in the landing configuration, and the radar altimeter indicating less than 800 feet. In addition, there was a verbal caution alert for glide slope deviations that was activated when the radar altitude was indicating less than 1,000 feet, and the airplane was more than 1.3 dots low on the glide slope.

The captain's total flight experience was about 7,500 hours, with 142 hours in the Boeing 757. His previous position was a Boeing 747 first officer. The captain reported that he had initially planned on having 7,200 pounds of fuel onboard upon arrival at Baltimore. However, with a delayed departure, and en route speed restrictions, the fuel reserve had decreased to about 5,800 pounds. The captain reported that he wanted to land with a minimum of 4,000 pounds of fuel onboard, and estimated the airplane would burn 2,000 pounds in the go-around. However, upon further questioning by personnel from the Northwest Airlines safety department, the captain said his estimates were based upon his previous Boeing 747 experience, and he admitted that the go-around could have been accomplished with less fuel burn than he had initially calculated.

NTSB Probable Cause

The captain's failure to follow existing company procedures for stabilized approach, and use of speed brakes.