What happened
On February 7, 2017, a Boeing 738 was performing a takeoff from EPMO when the crew experienced a physical impact and noise during the rotation phase. The pilot described a sensation where the nose wheel felt "stuck" to the runway, requiring increased force to lift. Once the nose wheel released, the aircraft rotated much more rapidly than expected, resulting in a tail strike.
Following the impact, the crew correctly identified the tail strike and initiated the appropriate emergency procedures from the Quick Reference Handbook (QRH). The aircraft returned to the departure airport, where it entered a holding pattern for approximately 90 minutes. This delay was necessary to burn fuel and reduce the aircraft's weight to meet the maximum landing weight (MLW) limitations for EPMO. All passengers and crew evacuated the aircraft safely after landing.
The investigation
The investigation examined the aircraft's flight data, including the Operational Flight Data Recorder (OFDM) and WQAR analysis performed by Boeing. Investigators reviewed the de-icing process, noting that a two-stage de-icing procedure had been completed. The crew had requested de-icing for the lower surfaces of the wings due to observed ice.
Technical analysis focused on the rotation dynamics, specifically the pitch angle and the activation of automatic slats. Data showed the aircraft reached a pitch of 12.74° during rotation, exceeding the 11° threshold specified in the Boeing Flight Crew Training Manual that can trigger a tail strike. The investigation also looked into the crew's use of the TALPA matrix and the completion of the low-temperature checklist, noting that the control surface check portion of the checklist was not completed.
Findings
Several contributing factors were identified that may have reduced the clearance between the tail skid and the runway surface:
- A momentary stagnation in airspeed during the rotation phase.
- A movement of the control column that triggered the deployment of spoilers, subsequently reducing lift.
- The activation of automatic slats at a pitch angle of 13.71° and an airspeed of 162 kts.
- The possibility of engine thrust being reduced during the takeoff roll.
While the investigation considered whether runway contamination or aircraft contamination (ice or snow) played a role, the findings did not definitively establish these as primary causes. The investigation could not determine a single, direct cause for the event, as the combination of factors observed during the takeoff could not be fully replicated in computer simulations without additional unmodeled variables.