1

One often reads of a "suspected tail-strike" at take-off (for example suspected because a controller has seen something from the tower, or because a cabin crew member sitting at the back of the plane has felt a jolt or heard a noise).

What puzzles me is why this must remain merely "suspected" until an inspection.

As an example, a 737 suffered a tail strike that appears to have at least been considered a possibility by the crew. Apparently doubting that it actually had occurred, the flight crew continued to their destination; had there been a clear indication, they presumably would not have.

Aircraft are festooned with external sensors and measuring devices; I would expect aeroplanes susceptible to tail strikes to have sensors measuring movement of, deformation of or contact with a plane's skid plate, to provide a cockpit alert, so that there need not be any doubt.

Since this often doesn't appear to be the case, there must be good reasons why such systems are not usefully employed - what are they?

Daniele Procida
  • 12,858
  • 2
  • 51
  • 94

2 Answers2

1

On one hand tail strikes are mitigated long before the need for a sensor. Aircraft makers generally address it from a design standpoint before the aircraft ever flys. If that is not enough control augmentation or tighter procedures are developed to prevent it from an operational level.

Ultimately such sensors do exist and do warn the crew of a tail strike they may just not yet be certified or installed on every airframe. For example it came in handy in this incident:

After the passengers had disembarked, the captain conducted an inspection of the tail skid of VZR and noticed some paint damage and scrape marks, however the cartridge containing the sensor for a tailstrike was still intact. This indicated that the tailskid had only just contacted the runway during the take-off.

Dave
  • 101,073
  • 5
  • 220
  • 364
  • 1
    Dave, in your second paragraph: how does the link relate to the statement? I visited the page and could not find anything about active sensors. – bogl Jun 14 '19 at 09:17
  • @bogl sorry bout that, I have updated it with a more relevant link and quote. I must have just thought that page had the info. It should be there now. – Dave Jun 14 '19 at 13:51
1

On aircraft not having a tail strike detector it relies on the captain to declare a tail strike that he encountered at takeoff or even at landing however, it is the responsibility of the captain to decide to continue the flight or not, nevertheless:

  • at landing the maintenance team should inspect the aircraft and if a noticeable damage is seen, they do a report

  • The technical crew(pilot...) is suppose to go around its aircraft and inspect any visible damage, this is done every time a technical crew is in charge of a flight

  • Slight tail strike doe not cause any damage and may not be felt by the crew, however when it is very slight it is felt only by the cabin crew at the rear of the aircraft, in this case they are supposed ...to inform the captain, and make a cabin report.

All modern aircraft do have a tail strike detectors B777, 787, all Airbus etc

The causes of tail strikes are numerous, even though long aircraft do have this tendency and are protected for such event as the A321, whose fly by wire prevents this as possible, also it has a detector, and a memorized maintenance message.

A tail strike having caused damages should be repaired as recommended by the aircraft manufacturer otherwise it might be subject to a crash by flight control failure of the trim or of the elevators as happened to a Boeing 747, as documented here.

The causes of tail strikes are mainly:

  • Improperly Set Elevator Trim or Mis-Trimmed Stabilizer

  • Rotation at Incorrect Speed or excessive rotation rate

  • Improper Use of the Flight Director : The autopilot, of course, is not to be used for take off, but only when airborne after a certain altitude, if the F/D is displayed, also, the pilot should not follow its pitching order at rotation but only after; all Boeing and Airbus FCOM explain this.

  • Unstabilized Approach - flight crews who continue an unstabilized approach below 500' AGL will likely never get the approach stabilized. The result is a tendency toward large power and pitch corrections in the flare, often culminating in a substantial nose up pull at touchdown followed by a tail Strike.

  • Excessive Hold Off in the Flare and the pilot instinctively increasing pitch to try to prevent a hard landing. The resulting nose high attitude can lead to a tail strike. A good landing is one made at the right speed and close to the optimum touchdown point at a reasonable rate of descent.

At this website you will find every detail about tail strikes the causes, their effects, the training to avoid them etc.

FreeMan
  • 16,245
  • 16
  • 87
  • 166
user40476
  • 1,772
  • 9
  • 27