Need Advice on Approaches

1st Official Post

    Need some tips that are more helpful than “pitch for speed throttle for alttitude” I try to follow the lear 45 VREF approach speed and stay in the PAPI glideslope but i always fall below the lights. When i try to stay in the papi lights i try to keep my vref speed but that means higher throttle and im approaching with nose above the horizon which is a big no no. Using pitch for speed and throttle for alttitude doesnt really work because if i see the papi lights show im too low i increase throttle while pitching to keep my speed, even just microadjusting the throttle, and theres a HUGE delay in power so im already falling way too low for it to fix anything or i shoot way above the glideslope way above where i want to be. It feels like i cant just stay in the exact glideslope.

    How do you stay in a glideslope while keeping your VREF speed, nose below the horizon until 50 feet above runway, when the engines take so much time for power adjustment

    • Official Post

    The Learjet 45 has engines mounted above the vertical centerline so adding thrust just pushes the nose down and can cause a higher descent rate while accelerating the aircraft before it pitches up eventually due to excessive airspeed. In a Learjet 45 and aircraft like the A320 with fly by wire with long term flight path stability the technique "thrust for speed, elevator for altitude" is usually the better technique. For the Learjet 45 in particular you kind of have to counter the additional nose down tendency from increasing thrust by adding a bit of upwards elevator. Early and slow adjustments usually work best.

    This is very different to the behavior of a typical Cessna 172 or even 737 and Boeing 777 or 787 with fly by wire with long term speed stability where increasing power or thrust pushes the nose up and reduces descent rate. In the C172 (and a lots of other aircraft) adding power actually slows you down long term and reducing power actually speeds you up. There the technique "pitch for speed and power for altitude" works better because power actually does the opposite of what you'd think.

    Regards,
    Jan

    Quote from Jet-Pack (IPACS)

    The Learjet 45 has engines mounted above the vertical centerline so adding thrust just pushes the nose down and can cause a higher descent rate while accelerating the aircraft before it pitches up eventually due to excessive airspeed. In a Learjet 45 and aircraft like the A320 with fly by wire with long term flight path stability the technique "thrust for speed, elevator for altitude" is usually the better technique. For the Learjet 45 in particular you kind of have to counter the additional nose down tendency from increasing thrust by adding a bit of upwards elevator. Early and slow adjustments usually work best.

    This is very different to the behavior of a typical Cessna 172 or even 737 and Boeing 777 or 787 with fly by wire with long term speed stability where increasing power or thrust pushes the nose up and reduces descent rate. In the C172 (and a lots of other aircraft) adding power actually slows you down long term and reducing power actually speeds you up. There the technique "pitch for speed and power for altitude" works better because power actually does the opposite of what you'd think.

    This is life saving advice because i was hard convincing myself that somehow i just needed to do the technique “better” but understanding why the learjet45 doesnt feel like it responds to this method is immensely helpful