Language selection

Air transportation safety investigation A14O0165

The TSB has completed this investigation. The report was published on 06 July 2016.

Table of contents

Loss of control

ExpressJet Airlines
Embraer EMB-145LR, N16954
London, Ontario, 53 nm W

View final report

The occurrence

The ExpressJet Airlines Embraer EMB-145LR, flight number 4538 (registration N16954, serial number 145072) departed Grand Rapids, Michigan, on an instrument flight rules flight destined for Newark Liberty International Airport, Newark, New Jersey. After departure, the aircraft deviated north of its desired track to avoid thunderstorms and climbed to its cruising altitude of flight level 370. At approximately 1915 Eastern Daylight Time, the aircraft flew through a large thunderstorm and encountered severe turbulence. The flight crew lost control of the aircraft, and it descended rapidly, losing approximately 4000 feet before the flight crew were able to regain control. The aircraft continued to its destination, where it landed safely. There were no reported injuries to the 3 crew members or 26 passengers, and the aircraft was not damaged.

Media materials

News release


Severe turbulence led to loss of control of an ExpressJet flight in September 2014 near London, Ontario
Read the news release

Investigation information

Map showing the location of the occurrence


Photo of Ken Webster

Ken Webster joined the TSB team in 2005, and works as Manager, Regional Operations out of the Ontario office. Mr. Webster has been investigator-in-charge in numerous TSB investigations, and assisted in several others, involving airplane, helicopter and air traffic control. Prior to the TSB he worked in civil aviation for 20 years, in several different capacities. As a pilot, Mr. Webster has flown numerous aircraft types throughout Canada and the US.

Class of investigation

This is a class 3 investigation. These investigations analyze a small number of safety issues, and may result in recommendations. Class 3 investigations are generally completed within 450 days. For more information, see the Policy on Occurrence Classification.

TSB investigation process

There are 3 phases to a TSB investigation

  1. Field phase: a team of investigators examines the occurrence site and wreckage, interviews witnesses and collects pertinent information.
  2. Examination and analysis phase: the TSB reviews pertinent records, tests components of the wreckage in the lab, determines the sequence of events and identifies safety deficiencies. When safety deficiencies are suspected or confirmed, the TSB advises the appropriate authority without waiting until publication of the final report.
  3. Report phase: a confidential draft report is approved by the Board and sent to persons and corporations who are directly concerned by the report. They then have the opportunity to dispute or correct information they believe to be incorrect. The Board considers all representations before approving the final report, which is subsequently released to the public.

For more information, see our Investigation process page.

The TSB is an independent agency that investigates air, marine, pipeline, and rail transportation occurrences. Its sole aim is the advancement of transportation safety. It is not the function of the Board to assign fault or determine civil or criminal liability.