Outlook for STOL Operations - ATR-42 STOL Cancellation

What does ATR scrapping their ATR-42 STOL (Short Take-off and Landing) variant due to lack of sales tell us?

ATR securing a reported 20 provisional orders for the STOL variant over several years suggests little market interest in this product, which involved a more powerful engine, and a larger rudder to shorten take-off distances and improved braking and spoiler deployment to reduce landing distances.

Photo - ATR Website Media

Are electric STOL (eSTOL) aircraft out-competing STOL turboprops in this category?

Possibly! The slightly smaller hybrid-electric Heart ES-30 has attracted various commitments from several operators serving relatively small, remote communities in areas with considerable natural barriers (water and mountains).

The expected flight distances are also short, which suits the hybrid-electric propulsion system.

However, other than Air Canada's investment in the programme, it's unclear how committed the other expressions of interest are, i.e. how much cash changed hands.

Is there a more generally limited market demand for STOL at this size?

The STOL market sits between conventional or CTOL aircraft (economic focus) and Vertical or VTOL (accessibility focus).

I see the golden age of STOL as the late 1940s to the mid-1960s when no significant civilian VTOL capacity existed, surface transportation was generally slow in comparison to STOL aircraft, and the levels of air traffic were much lower.

This period saw the introduction of types such as the DHC-2 through to -6, the PC-6 and An-2 connecting small remote communities to each other and larger settlements. Many of these aircraft remain in service, although incorporating various engine, propeller and flight deck enhancements. Consequently, few new types entered the market since then.

It is due to various changes.

Civil helicopters offer air access to almost any open space if accessibility is important, at higher costs than STOL (higher aircraft costs, but lower infrastructure costs). This eroded the bottom end of the STOL market.

Various other factors attacked the upper end of the STOL market.

Faster or more extensive road networks and bridges over water barriers permitted much lower cost surface transportation costs. As an extreme example, think of the TV series 'Ice-Road Truckers'; the Ice-Roads were developed from the 1950s onward. Larger modern road freight vehicles can accommodate >20-30 loads, equivalent to 4-6 ATR-42 flights (many more DHC-3 or -6 flights).

Growing community populations often lead to increased traffic levels which justifies building longer runways for more efficient CTOL aircraft (if the land is available) with lower ticket prices. Ironically, a successful STOL operation, i.e. growing traffic, enhances the case for an extended runway as it demonstrates the demand for air transportation.

These effects have pushed STOL aircraft toward the fringes of aircraft usage, with many converted to float planes that make use of open water around small settlements on remote islands.

Time will tell whether the various aircraft eSTOL aircraft being developed will revive STOL operations beyond the current limited networks served by the venerable STOL types.

Perhaps, congested surface transportation is a critical enabler for more STOL operations, although the congestion itself highlights the inherent cost advantages and convenience of surface vehicles.

However, I believe that VTOL (helicopters and possibly eVTOL) will continue to dominate STOL aircraft at the lower end where accessibility is the priority.