What happened
On February 15, 2023, at approximately 07:50 local time, two agricultural aircraft, an Air Tractor AT-401 (registration HK4077) and an Air Tractor AT-301 (registration HK5177), were involved in a mid-air collision near Ciénaga, Magdalena. Both aircraft, operated by the same company, were performing aerial spraying operations near the La Lucha aerodrome (SKGM).
As the pilot of HK4077 was on final approach to runway 32, the aircraft was struck on the vertical stabilizer by HK5177, which was also maneuvering to land. The impact caused the detachment of part of the rudder and significant deformation of the vertical stabilizer on HK4/077. The pilot of HK5177 experienced damage to the left wing tip but was able to continue the approach and land normally. Following the collision, the pilot of HK4077 performed two low passes over the runway to assess the aircraft's structural integrity. After receiving confirmation from ground personnel regarding the damage to the stabilizer, the pilot completed a normal landing. Both pilots were uninjured, though both aircraft sustained substantial damage.
The investigation
The GRIAA investigation examined the flight paths, maintenance records, and communication protocols used during the operation. Investigators analyzed the collision dynamics, determining that HK5177 struck HK4077 from left to right in an ascending attitude.
The investigation also reviewed the radio communications on the shared frequency (Channel 2) and the operational procedures established in the company's Manual of Ground Operations (MGO). It was noted that while visibility was slightly reduced by smoke from nearby crop burning, horizontal visibility remained sufficient for VFR operations and was not a contributing factor. The investigation also looked into the cockpit ergonomics, noting that the lack of functional Push-to-Talk (PTT) buttons on the control sticks forced pilots to divert their attention from the external environment to operate the radios.
Findings
- Failure to adhere to established radio and air traffic procedures during operations in uncontrolled airspace.
- Deficient communication between the two crews regarding their positions and intentions.
- Inadequate radio discipline, with Channel 2 being used for non-operational conversations.
- Lack of operator oversight regarding crew compliance with internal traffic and radio procedures at the operating base.
- Distraction due to cockpit configuration, as pilots had to look down to manually operate microphones, reducing situational awareness.
- Improper flight configuration of HK5177 at the time of impact, which did not align with the company's standardized approach procedures.