2015.07.26.Crash

Tail part of the ailplane crashed

Chofu and Oshima

Trajectory estimated

2015.07.26.Crash referes to catastrophe of small airplane Piper PA-46-350P, registered JA4060, near the Chofu airport, soon after take-off

Few strange details from the original reports about that crash are mentioned below.

Overview

The report suggests the following summary:

On Sunday, July 26, 2015, at around 10:58 Japan Standard Time (JST: UTC + 9hrs:unless otherwise stated, all times are indicated in JST using the 24-hour clock), a privately owned Piper PA-46-350P, registered JA4060, crashed into a private houseat Fujimi Town in Chofu City, right after its takeoff from Runway 17 of Chofu Airport. There were five people on board, consisting of a captain and four passengers.
The captain and one passenger died and three passengers were seriously injured. In addition, one resident died and two residents had minor injuries.The aircraft was destroyed and a fire broke out. The house where the aircraft had crashed into were consumed in a fire and neighboring houses sustained damage due to the fire and other factors.

Destination was Oshima Airport.

Speed and altitude

Figures as left show reconstruction of trajectory of the aircraft before the crash, images are from the same report .

The red curves shows altitude of the aircraft versus time (JST) and versus distance from the runway threshold. Following the old tradition (established before discovery of the rotational symmetry of the space), the length is measured in meters, while altitude is measured in foots.

Figures show, that at 40:57:45, the aircraft passes the threshold at altitude 25 ft with seed 87 knots.

Figure 1.16.5.4, at page 60 of the same report, indicates that, approxmately at this moment, namely, at 10:57:50, the landing gear is retrtacted. Perhaps, the retracting of the landing gear takes of order of 5 second; so, the deviation of 5 seconds is not significant.

Then, the aircraft seems to loss the control; the pitch and speed become chaotic. The shaking leads to loss of speed, and the aircraft falls down to the living blocks. In the report, the coincidence of the retracting gear and loss of the control is not discussed. In the next section, this coincidence is discussed; the lost of control is interpreted as result of some defect or mechanism that is switched on at the retraction of the landing gear.

Hypothesis

The problem of the aircraft reveals at the retracting of the landing gear.

The figures indicate, that, after an attempt to retract the landing gear, the aircraft losses its performance; both speed and pitch become chaotic. In addition, the speed, instead of to increase (due to reduction of the aerodynamic drag of the wheels), reduces.

Figure 2.16.5.7(3) at page 63 confirms, that the landing gear was not successfully retracted at least until 10:57:53. (After the retraction of the landing gear, the lighting of the gear indication is supposed to be off.)

At this moment, the aircraft lost its performance, losing both speed and altitude.

The coincidence above could be interpreted with hypothesis, that some bad device had been installed in the place, where the wheels of the aircraft are supposed to be folded. The squeezing had affected the cables from the cabin to the tail, and leaded to the lost of control.

Perhaps, the pilot tried to regain the control, accelerating the aircraft in various directions, but the reserve of speed and altitude was not sufficient to allow the pilot to release the landing gear back, in order to regain the control of the aircraft and to perform the emergency landing at the same airstrip.

The hypothesis above significantly differs from the interpretation in figure 3.5.3. from the Report. According to that figure, the pilot took-off a hundred meters before the optimal position (and before he got the speed sufficient for the safe launch.)

Gallery

page 60, Figure 2.16.5.4 Estimated Flight Route.

Keywords

2015.07.26.Crash, Crash, English, Japan