What happened
On 24 October 2021, Runway 3 at Changi Airport was closed for scheduled maintenance work. During this closure, a contractor team was performing obstacle light installation at a site located beyond the northern end of the runway. To reach their worksite, the team used a crane vehicle to transit via the closed runway and an adjacent service road.
At approximately 1100LT, the runway was scheduled to reopen to accommodate an incoming flight. Although the team was instructed to remain at their worksite during the reopening, the crane vehicle departed the worksite and entered the runway at about 1100LT. An air traffic controller noticed the vehicle traveling southwards on the runway and alerted the relevant authorities. The runway was temporarily closed to escort the vehicle away, and the aircraft landed safely at 1123LT after the runway was cleared.
The investigation
An investigation by the TSIB examined the communication and operational procedures in place during the maintenance period. The inquiry focused on why the crane vehicle entered the active runway and why the contractor team departed their worksite despite prior arrangements.
Investigators looked into the instructions provided by the Runway Entry/Exit Point (REP) Officer. While the officer had called the site supervisor to remind the team to remain stationary, the supervisor reported that high noise levels at the worksite prevented him from hearing the full message. The supervisor mistakenly believed the instruction was to return to the REP Hut, and he did not seek clarification.
Findings
- The supervisor's failure to seek clarification regarding a misunderstood radio/phone message was a primary factor in the vehicle's movement.
- There was a lack of clear documentation regarding the restriction on using the runway or service roads as transit paths for worksites located outside the runway area.
- The boundary between the runway/taxiway area and the external worksite area was not clearly defined, leading to confusion among contractors.
- The aerodrome operator had not explicitly communicated to contractors that they were required to use perimeter roads for accessing external sites.
- There were inconsistencies in the enforcement of contact person requirements for crane operations.
Safety action
Following the investigation, the aerodrome operator updated its Airport Operational and Safety Requirements (AOS) manual. The revised procedures now clearly define the area bounded by the runway strip and RESA as the controlled zone. New rules prohibit contractors from using the runway to access external worksites and mandate the use of perimeter roads. Additionally, the operator has implemented a requirement for contractors to register their intent to enter the runway at least three days in advance and has increased the frequency of on-site inspections.