Air transportation safety information A19C0136-D1-L1

200 Promenade du Portage
Gatineau QC  K1A 1K8

16 December 2019

Letter addressed to:
Director General, Civil Aviation
Transport Canada

Re :

AVIATION SAFETY INFORMATION LETTER A19C0136-D1-L1 de Havilland Aircraft of Canada DHC-8-102 – Aircraft Flight Manual / Quick Reference Handbook – Emergency Procedure (WT ON WHEELS)

On 22 October 2019, a de Havilland DHC-8-102 aircraft (registration C‑FABA, serial number 092) operated by Wasaya Airways,  was conducting cargo flight WSG815 from Pickle Lake Airport (CYPL), Ontario, to Fort Severn Airport (CYER), Ontario, with 3 crew members on board.

While enroute, the weight on wheels (WOW) caution light illuminated. The quick reference handbook (QRH) “WT ON WHEELS” (Caution Light) procedure was consulted and the crew decided to return to CYPL. During the return trip, the WOW caution light went out and then illuminated once more when the aircraft was on the approach to CYPL. The crew proceeded with the landing on Runway 09 at CYPL.

On touchdown, several caution lights illuminated on the caution/warning annunciator panel. During the landing roll, the aircraft did not respond to nose wheel steering input via the tiller. As the aircraft’s speed decreased to below 30 knots, the captain applied brake input but the aircraft brakes did not respond. The aircraft veered off the runway and came to a stop approximately 100 feet off the north side of the runway. There were no injuries. The aircraft sustained minor damage.

The operator’s maintenance personnel performed an inspection of the landing gear system and found two faulty weight-on-wheels proximity sensors. Data collection for this Class 5 occurrence (A19C0136) has been completed.

The emergency procedure specified in the de Havilland DHC-8-102 aircraft flight manual (AFM) and the QRH (Figure 1), which the flight crew consulted, state the following:

Figure 1. Weight On Wheels Procedure (Source: de Havilland Quick Reference Handbook, page 14.5)
Weight On Wheels Procedure (Source: de Havilland Quick Reference Handbook, page 14.5)

(Caution Light)

Caution: Landing Gear may not retract.
Note: Caution Light may extinguish after landing, however, maintenance action will be required prior to next flight.

The current emergency procedure listed in the AFM/QRH do not address the multiple system failures that can occur if the source of the “WT ON WHEELS” caution light is the failure of two proximity sensors rather than just one; therefore, following the current emergency procedure may lead to similar occurrences.

This occurrence demonstrates the need to provide specific information in the AFM/QRH “WT ON WHEELS” (Caution light) procedure regarding the possibility that the aircraft may not respond to anti-skid brakes and nose wheel steering input if two proximity sensors have failed. Therefore, Transport Canada (TC) is encouraged to work with the manufacturer to amend the “WT ON WHEELS” emergency procedure currently contained in the AFM and QRH.

The TSB limited its data gathering to the DHC-8-102 series; however, this issue may also be present in other DHC-8 series aircraft. The TSB would appreciate to be advised of TC’s position on this issue, and what, if any, action is taken in this regard.

Yours sincerely,

Original signed by

Natacha Van Themsche
Director of Investigations — Air
Transportation Safety Board of Canada


  • Acting Director Policy and Regulatory Services, Transport Canada
  • Chairman, Longview Aviation Capital
  • Chief Operating Officer, de Havilland Aircraft of Canada Limited
  • Senior Accident Investigator, de Havilland Aircraft of Canada Limited
  • Director of Flight Operations, Wasaya Airways

Background information

Occurrence No.: A19C0136

This Safety Communication No.: A19C0136-D1–L1

Date modified: