Download This Article (PDF - 320 KB)TRAINING RECOMMENDATIONS AND PREVENTIVE MEASURES
Tail strikes can be prevented. The most effective means of prevention is a training program that reinforces proper takeoff and landing procedures. There are a number of steps both management and flight crews can take to help prevent tail strikes.
Management:- Ensure instructors and evaluators stress proper landing and takeoff techniques during all training and evaluations.
- Make “tail strike prevention” part of the safety program through posters, briefings, videos, computer-based training, and other elements which are available from Boeing Field Service representatives.
- Make tail clearance measuring tools available in the simulator for all takeoffs and landings during simulator training and evaluations and provide feedback to crews.
- Use a self-measuring tail strike operational tool in the airline’s fleet (see “Crew” section).
- Ensure that flight operational quality assurance programs are not used as a punitive device.
Crew:
- Adhere to proper takeoff and landing techniques.
- Never assume—double-check the takeoff data, especially if something doesn’t look right. Coordinate insertion of the zero fuel weight (ZFW) in the Flight Management Computer with another crew member. Double-check data with the load sheet. Inaccurate (low) ZFW entries have caused significant tail strikes.
- Know your airplane—have an idea about the approximate takeoff and approach speeds.
- When setting airspeed bugs, always do a “reasonable check.”
- Be aware of the differences between models and types, especially when transitioning from other equipment.
- If a tail strike occurs, follow the checklist.
- Crew resource management should be an integral part of training. Crews can get complacent during routine operations, yet a real threat exists during operations in strong gusty crosswinds. How the crew plans for and mitigates the threat can make the difference between a safe takeoff or landing and one that results in a tail strike. Every crew should have a plan for identifying and discussing the threat. For example:
- The entire crew should review appropriate crosswind takeoff procedures and techniques for operating in strong gusty winds.
- The pilot flying (PF) should review threat strategy for the takeoff or landing with the pilot monitoring (PM).
- The PM should monitor airspeed versus rotation callout to the PF and identify airspeed stagnation during the rotation phase to takeoff target pitch attitude.
- If the first officer is making the takeoff, the captain should monitor pitch rate and attitude and call out any deviations and be prepared to intervene.
Other approaches include a self-monitoring tail strike analysis tool that provides a pitch report for every takeoff and landing. If the tail gets within 2 degrees of a potential tail strike, an auto printout is provided to the crew after the respective takeoff or landing. Airlines that have adopted this program have had significant drops in tail strike rates.
Preventive measures.
Boeing is actively developing tail strike preventive measures. Some 777s have two additional features that help prevent tail strikes: the semi-levered main gear and tail strike protection.
Boeing 777 semi-levered main gear.
Because the vast majority of the weight of the airplane is borne by the lift of the wings at the time of rotation, the semi-levered gear acts as if it were “pushing” down like a longer gear. This allows a higher pitch attitude for the same tail clearance or more clearance for the same pitch attitude. A hydraulic strut provides the energy to provide this increased takeoff performance. Although designed to increase takeoff capability, the system provides increased tail clearance for the same weight and thrust as nonequipped airplanes.
Boeing 777 tail strike protection.
Timely elevator input can help avoid tail strikes on both takeoff and landing. The tail strike protection command (TSP CMD ) is summed with the pilot’s input to form a total elevator command. The TSP CMD is limited in size to 10 degrees, which allows the pilot to overcome its effects, if desired, by pulling the column farther aft. The size of the TSP CMD is controlled by excessive tailskid rate relative to a nominal threshold of tailskid rate, and by excessive nearness of the skid to the runway, relative to a nearness threshold. Different thresholds are used for takeoff and landing. The TSP CMD is limited to commanding nose down increments only. Tailskid height and rate are computed from radio altimeter signals, pitch attitude, pitch rate, vertical speed, and the length between the radio altimeter location and the tailskid location. A complementary filter is used to provide acceptably smooth rate and height signals. Provisions are included to account for the bending of the forward fuselage when the nose wheel gear lifts off the ground.
SUMMARY
Tail strikes are preventable. If standard recommendations are followed for all Boeing models, the chance of tail strikes is greatly reduced. There are additional challenges and solutions when operating during strong crosswinds and gusty winds. Training is the key to preventing tail strikes. Technology enhancements can also contribute to solutions for Boeing production airplanes. For more information, contact Capt. Dave Carbaugh at david.c.carbaugh@boeing.com.
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