Thankfully this detailed (but old) article is still online. Must admit to not remembering a lot of it (why? because I ain't gonna be flyin' the C anytime soon). So there is a button on the stick which may have been inadvertantly deselected but as usual I can only GUESS.
Tailored to Trap 01 Dec
2012 Frank Colucci
http://www.aviationtoday.com/av/mili...rap_77964.html
"“F-35C control laws give Navy pilots Integrated Direct Lift Control for easier carrier landings, and they open the door for future landing aids.
Joint Strike Fighter (JSF) test pilots in July [2012] began using an Integrated Direct Lift Control (IDLC) scheme meant to improve approach performance and reduce pilot workload in carrier landings. Tailored control responses in part differentiate the carrier-based F-35C from its runway [F-35A] and small-deck [F-35B] siblings. Lockheed Martin test pilot Dan Canin at Patuxent River Naval Air Test Center, Maryland, explained, “What IDLC does is improve the flight path response of the airplane, allowing the pilot to make almost instantaneous corrections to glideslope while maintaining a constant angle of attack.” “The landing approach in the F-35C is flown with the stick only,” noted Canin.
“The throttle is automatic.”... [Don't know if it is possible to 'manually control the 'thrust request']
...…“With IDLC, we change the symmetric deflection of the flaps and the ailerons in response to pitch and throttle commands by the pilot. The glideslope response is immediate, and doesn’t require a speed or alpha change. This is a tremendous advantage over a stiff-wing airplane.”….
…“It’s an integral part of the flight control system and responds to the pilot’s normal stick and throttle movements, without requiring a separate control.” The flight control system also compensates for the pitching moments induced by the lifting surface deflections — F-35C ailerons pitch the airplane on approach almost as much as the big horizontal stabilizers — to maintain the proper angle of attack.
IDLC is commanded by an Approach Mode Control button on the F-35 active inceptor stick. “You really could have done this with any other airplane,” acknowledged Canin, “but the implementation would have been more complicated.” He added, “It’s easier and cleaner to do this with a flight control system that’s naturally a pitch-rate-command system.
...All three variants of the F-35 provide some measure of IDLC. “Glideslope is always important,” observed Canin. “Anything you can do to improve flight path control on approach is a good thing. Waveoff performance is also improved with IDLC, since it can stop or reduce your rate of descent while you’re waiting for the engine to spool up.”
The IDLC function is not identical in all the three F-35 variants, however. “The IDLC gain is much higher in the C-model than the other two,” said Canin. “We only have one release of software for the three variants. It configures itself when it wakes up and discovers which type of F-35 it’s in.” The F-35B does not use IDLC at all in jetborne (vertical landing) mode, when aerodynamic control surfaces are fixed.
Even with its innovative flight controls, the F-35C, from the pilot’s perspective, is relatively conventional coming aboard the carrier. “Determining where you are with respect to lineup and glideslope is all visual,” acknowledged Canin. “For lineup, you look at the ship and line up on centerline … easy enough if the ship’s heading is steady, but tricky if the ship is wallowing,” noted Canin. “As for glideslope, you have to watch the meatball and see small deviations. Then you have to put the ball back in the middle, with the right rate of descent so it stays there. None of that’s changed with this airplane, but what we’re giving the pilot is more responsiveness and bandwidth to do that.”..."
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DFP quotes from
DOT&E report
2016:
http://www.dote.osd.mil/pub/reports/ FY2016/pdf/dod/2016f35jsf.pdf
"...The VFA-101 pilots reported that the Delta Flight Path mode of operation made carrier approaches easier on pilot workload and touchdown points more consistent. During the qualifications, pilots made 154 approaches and landings with 100 percent boarding rate and no bolters…."
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"...The JSF, in a low speed approach to a carrier landing, will descend at about
11 fps [seen on the ILARTS screen low right corner], and will withstand sink rates up to almost
18 fps. By comparison, the typical sink rate for an Air Force JSF will be about two ft/sec.... The Navy JSF currently flies landing approaches at about 130 to 135 knots, about 25 knots slower than the Air Force version....”
http://machinedesign.com/article/the...l-reasons-0307 [2002]