Steve Askin was born for action, thrived on danger and knew the risks.
Fighting the enemy on the ground as a decorated soldier in the SAS, he was given the tools of war to protect and kill. Fighting fires in the air, he had his helicopter at his fingertips.
Mr Askin held a commercial helicopter pilot's licence and had approximately 2350 hours of flying, 80 of those fighting fires. But he died when his helicopter crashed fighting the Port Hills fires in February. What happened?
Firefighter's fateful day
Mr Askin took off in a Squirrel helicopter at 5:40am on February 14, 2017 to re-join the Christchurch firefighting operation on the Port Hills. What he didn't know that Valentine's Day was that he wouldn't make it home to see his wife and their two children again.
He spent the morning above the flames in his helicopter with a monsoon bucket swinging below. After lunch he led three helicopters dropping water near the Sign of the Kiwi at the top of the Port Hills.
Every three to four minutes they did a circuit, hovering over a pond filling their monsoon buckets with water and then flying to the drop zone, dumping their load, and then heading back to the pond to refill.
At 2:05pm, after dropping a bucket full of water on the flames, Mr Askin headed back to the pond.
The interim report published this week by the Transport Accident Investigation Commission (TAIC) found that on his approach to the land, the cable attached to the helicopter and the empty monsoon bucket had flown up and struck the tail rotor with catastrophic consequences. The helicopter banked and rolled to the right until it hit the ground on impact. The main rotor and engine separated from the fuselage, while the tail rotor had separated from the tail boom.
In 2006 Eurocopter, the French manufacturer of the Squirrel, sent a service letter around the world to operators of their machines using slings. It warned that "the accident risk is higher than that of other missions due to its demanding nature" and wanted to "remind them of some lessons learned from analysis of accidents".
- do not take off with an empty bag or net
- use only bags or nets in good condition
- with unloaded slings, avoid descending at airspeeds above Vy (best rate of climb).
Eurocopter kept a six-year record of accidents involving sling work before 2006.
Types of accidents:
- sling striking the helicopter: 41 percent
- sling catching objects on the ground: 26 percent
- mechanical, engine or fuel problem: 26 percent
- Other: 7 percent.
Why did Steve Askin crash?
Mr Askin's crash, according to Eurocopter, fits into the most common category involving slings - the sling contacting the tail rotor.
The two main reasons for this are:
- a burst monsoon bucket or bag, or
- an abrupt dive manoeuvre.
When the monsoon bucket is empty it can act like a parachute and fly up towards the helicopter.
Industry sources told Newshub that a burst monsoon bucket is a rare occurrence.
Mr Askin was flying with the main door off. The maximum Vy (best speed for climb) is 70 knots; 65-70 knots when flying with a monsoon bucket.
On Valentine's Day it was turbulent and windy - a northwesterly was blowing from the west to east towards the Port Hills. Could this have aided the lifting of the monsoon bucket upwards as the pilot was descending towards the pond to refill?
The Transport Accident Investigation Commission is still to determine why the monsoon bucket flew up into the machine. It has ruled out the bucket hitting the ground and has also concluded that the main rotor damage was consistent with the rotor having been driven by the engine at impact.
The final report will be released in 2018.