Precision Landing Mode upgraded, makes strike pilot landing smoother

An F/A-18F Super Hornet with VX-23 performs a touch-and-go aboard USS John C. Stennis (CVN 74) while engineers monitor testing from the flag bridge.

The first version of Precision Landing Mode (PLM) for the F/A-18E/F Super Hornet and EA-18G Growler did away with much of the stress on pilots flying behind a ship—and PLM Version 40 (V40) intends to do away with most of what remains.

VX-23 continues to test PLM software with a wide array of flight control and other aircraft malfunctions in hopes of delivering a more robust and redundant product for the fleet. The test team’s ultimate goal: make PLM the default landing mode for all passes.

Last year, VX-23 executed shipboard testing with a variety of failed flight control surfaces that characterized flying qualities behind a ship. The team also tested the addition of a backup automatic throttle control (ATC) with the ability to control throttle response via communication from the flight control computer (FCC) to the full authority digital electronic control all through the mission computers, as opposed to analog wires in the event that normal ATC is not available.

In December 2019, the VX-23 Carrier Suitability Department took one Super Hornet and one Growler aboard USS John C. Stennis (CVN 74) to test new software changes for incorporation in the fleet’s release of PLM V40. Most notably, V40 adds capability that allows pilots to fly PLM with a single angle of attack (AOA) probe failure, in gain override or with an Inertial Navigation System (INS) failure. Additionally, regular ATC is now available in the gain override mode, allowing pilots to fly a “normal PLM” approach even in the case of a complete AOA failure.

To safely test malfunctions such as the failure of an AOA probe or flight control surface, test aircraft are equipped with a unique feature called dial-a-function (DAF) in the aircraft’s FCCs. DAF allows the pilot to change individual numerical parameters within the flight control software itself to turn off flight control surfaces or mimic an AOA probe failure by sending a specific AOA value to the FCCs and mission computers. The pilot can remove any of these mimicked failures by pressing the paddle switch or performing a Flight Control System reset, returning the aircraft to a nominal condition.

Every carrier aviator knows that the easiest pass begins with an on-and-on start, but they also know not every pass starts that way. As such, VX-23 pilots evaluated aircraft performance on its ability to respond and correct from various off-nominal starts testing, including instances when a pilot commits intentional deviations at the start or in the middle that require correction prior to touchdown. Even in cases with extreme deviations (i.e., well below glideslope and lined up right in the middle), PLM performed admirably and proved capable of returning to glideslope and centerline prior to the ramp.

The pilot for that particular example pass was flying with the INS in standby mode. After the pass, the pilot stated simply, “I’d rather fly PLM standby than ever fly another manual pass.”

Version 40 promises to make PLM available in nearly every degradation that is still recoverable at the ship, greatly reducing a pilot’s workload during the final phase of landing and enhancing their concentration on other emergency-related tasks.

Fleet release of PLM V40 begins this year. Although not tied to any particular system configuration set (SCS), the full functionality and redundancy of PLM V40 is only available on aircraft with H10+ SCS or newer.