Hey Grumman pilots, my question is about the flaps setting during an instrument approach. I did my instrument in a 172 and for the approach we would always put in the first notch of flaps before the FAF and shoot for 100kts. Most of the flying I do is in a Tiger, and now that I can use it for instrument flying, my question for you all is how do you normally configure the airplane for the approach? Do you use 1/3 flaps or any flaps at all? What speed do you like to look for? The best thing I could do is go up with someone who has actually flown approaches in the Grumman, but I just wanted to hear all of your thoughts. Thanks!
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Grumman Tiger Instrument Approaches
- Thread starter Whenskey
- Start date
poadeleted20
Deleted
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- Apr 8, 2005
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My technique is to use 90 knots indicated airspeed (KIAS) as a baseline for all instrument approaches. This gives you enough speed to keep from bottlenecking the system, but not so much that getting down to landing speed is a problem. It’s comfortably in the white arc, allowing the use of flaps without further deceleration. And it makes picking the FAF-MAP times very easy.
For ILS approaches, I begin slowing three minutes/five miles from the final approach fix. This is easy enough to peg if you have a GPS (as we do), but a little harder if you’re just getting vectored around. (You can get a hint that you’re getting close when the controller turns you to within 30 degrees of the final approach course.) Slowing to 90 KIAS (105 mph) involves throttling back to about 2000-2100 RPM from cruise speed – you’ll see a further reduction in RPM to about 1900-2000 without touching the throttle as you slow. As the glideslope needle marches down, I lower flaps to one-third (three “potatoes” of switch-holding if you don’t want to look down at the indicator) and retrim. This helps slow the airplane and add drag, so you don’t have to fly the ILS at a CHT-chilling near-idle. As the GS needle centers, I reduce power to 1600-1700 RPM. This works well for 90 KIAS (105 mph), one-third flaps, 3 degrees of descent (obviously, headwinds will make for higher power settings). I keep this setup all the way to the middle marker even if I see the runway. At the MM, with runway in sight, I reduce power slightly and drop full flaps, adding forward pressure to prevent ballooning, and retrimming once the flaps are full down. Then, I let it slow to the normal 65 knots (75 mph) over the fence and land. If I don’t see the runway, I add full power, rotate the nose to 5 nose up, hit the flap switch up (you’re getting so little lift out of the flaps that you won’t sink at all), and retrim and rotate to normal climb attitude (about 7 nose up) as the flaps come up, accelerating to Vy until above 400 feet AGL and then accelerating to normal cruise climb speed.
For NoPT/vector-to-final non-precision approaches, I use pretty much the same technique as an ILS. For non-precision overhead approaches (beacon out to PT and back in), I plan to hit the beacon outbound at 90 KIAS (105 mph) clean and then add one-third flaps as described above, as though the beacon were the outer marker/GS intercept point. I always look for 500-700 fpm during descents to intermediate altitudes and MDA – this gives enough descent rate to get you down without making it hard not to bust through the floor. I leave the flaps at one-third all the way through the approach until I’m at the VDP, when I reduce power slightly and drop full flaps as at the ILS MM. Missed approach is the same as the ILS.
For ILS approaches, I begin slowing three minutes/five miles from the final approach fix. This is easy enough to peg if you have a GPS (as we do), but a little harder if you’re just getting vectored around. (You can get a hint that you’re getting close when the controller turns you to within 30 degrees of the final approach course.) Slowing to 90 KIAS (105 mph) involves throttling back to about 2000-2100 RPM from cruise speed – you’ll see a further reduction in RPM to about 1900-2000 without touching the throttle as you slow. As the glideslope needle marches down, I lower flaps to one-third (three “potatoes” of switch-holding if you don’t want to look down at the indicator) and retrim. This helps slow the airplane and add drag, so you don’t have to fly the ILS at a CHT-chilling near-idle. As the GS needle centers, I reduce power to 1600-1700 RPM. This works well for 90 KIAS (105 mph), one-third flaps, 3 degrees of descent (obviously, headwinds will make for higher power settings). I keep this setup all the way to the middle marker even if I see the runway. At the MM, with runway in sight, I reduce power slightly and drop full flaps, adding forward pressure to prevent ballooning, and retrimming once the flaps are full down. Then, I let it slow to the normal 65 knots (75 mph) over the fence and land. If I don’t see the runway, I add full power, rotate the nose to 5 nose up, hit the flap switch up (you’re getting so little lift out of the flaps that you won’t sink at all), and retrim and rotate to normal climb attitude (about 7 nose up) as the flaps come up, accelerating to Vy until above 400 feet AGL and then accelerating to normal cruise climb speed.
For NoPT/vector-to-final non-precision approaches, I use pretty much the same technique as an ILS. For non-precision overhead approaches (beacon out to PT and back in), I plan to hit the beacon outbound at 90 KIAS (105 mph) clean and then add one-third flaps as described above, as though the beacon were the outer marker/GS intercept point. I always look for 500-700 fpm during descents to intermediate altitudes and MDA – this gives enough descent rate to get you down without making it hard not to bust through the floor. I leave the flaps at one-third all the way through the approach until I’m at the VDP, when I reduce power slightly and drop full flaps as at the ILS MM. Missed approach is the same as the ILS.