Time for a Caribou replacement

The Caribou was to be replaced by C-295s or C-27J Spartans under Air 5190, but in 1999 during the critical Timor deployment, the decision (reportedly in favour of the C-295) was shelved. So the Caribou soldiered on for another decade and today King Air 350s are filling the flightline at 38SQN as an interim measure, building crew currency on a modern type, while a definitive Caribou replacement is due to be acquired under Air 8000 Phase 2. But that decision isn’t due for a few years.

So with the Army’s six CH‑47D Chinooks – to be replaced by seven CH-47Fs arriving from 2014 – aside, the Caribou’s retirement has left a big gap in the ADF’s medium airlift capabilities.

The absence of any fixed wing STOL transport serves to highlight that the Alenia C-27J would be a neat fit as a Caribou replacement.

The C-27J possesses excellent interoperability with the C-130J, sharing a similar cross-section and identical floor loading capability, plus common engines and components, and can also take CH-47 sized loads. Some countries use all three types and load many inventory items on all three, making trans-shipment easier. If our long experience, particularly in PNG, is a yardstick, the C-27J should suit, complementing the C‑130s which are not capable of landing on many of the short, soft airstrips around the region.

In war or major disasters in the region the new Navy heavy amphibious ships will be invaluable self-contained floating bases carrying large fleets of MRH 90 helicopters, but self deployed Chinooks and fixed wing aircraft provide faster, more flexible answers to many scenarios, especially where the need is widely scattered. Even cashstrapped Greece has increased its Chinook fleet to 16 (15 are still in service) to help meet firebombing and disaster relief and has also ordered 15 C-27Js.

What is never stated is that although the larger C-130 could air drop to places where only the C-27J can land, air drops to undisciplined civilians can be a dangerous exercise which can cause many casualties.

Also, if a C-130 cannot land on such a strip, it cannot extract any casualties.

After a slow start, Alenia is getting a spurt of C-27J orders, including from the USAF, which discovered it could not do without the C-27J’s G222 forebear, with the order book soon to reach 200.

But if we dither too long, the government may leave it too late, or dubiously decide we can do without such capability.

History from Vietnam onwards has proven that thinking wrong, and while civil transports have long been used in some Defence support roles, they have no STOL or poor strip capability and can’t be sent in harm’s way during a conflict.

Over 40 years there have been many methods of relating aircraft load footprints to poorer surface conditions. New Zealand, Samoa and PNG conditions bred systems based on wheel layout and weights against surface factors, but the globally used California Bearing Ratio (CBR) for unsealed fields provides a good basis for comparison. The near northern neighbours and our north suffer monsoon rains and poor strips. The C-47 with 48psi tyres had a CBR around 3-6, the Caribou 2-4, and the C-27J 2. 5-4 – or under half a C-130 – with the lower end of the range enabling access to many key strips, including in wet conditions. With tyres deflated to 27 psi, the Caribou was under two, although that could see the main tyres pulled off the rims in screw turns. The untouchable Turbo Porter fitted with Caribou wheels at just 14 psi was rated effectively CBR 0 and could operate where 4WDs bogged. Across our region, not just in PNG, many secondary and remote airfields have suffered due to funding shortages – all of which increase the need for a medium STOL.

The C-27J’s payload capabilities, low CBR, speed, excellent climb and range performance means that it stands out as the obvious choice between CH‑47s and C-130s, even if more of those are also procured.

But it won’t be built forever, and should British-like austerity measures take place in Defence we will be challenged to keep what we have on order today, let alone adding a badly needed new type.