Does the 3 degree approach make sense in VFR?

There is an air-facts-journal article on the "changing myths of aviation" and their suggestion to "keep your speed up" on final seems counter productive.



The article points to the need to understand an airplane's deceleration characteristics but it seems to imply the prevelance of the "straight in approach".

I get vectored in "relatively straight" at some Class C airports but not so much at smaller airports. I suspect the majority of "Cessna Pilots" the article refers to are at smaller and often uncontrolled airports.

I would presume a tighter pattern is a better disciple than a faster pattern.

BTW: if my calculations are correct for that diagram, a 3 degree approach with a 600fpm is about 110kts.

For a simple rule of thumb at the airlines we use ground speed / 2 and add a zero to get an est of required descent rate to achieve a 3:1 or 3 degree approach angle.

100kts gs would be about 500fpm descent rate

calculating backwards:

700fpm rate would be required for a 140kt ground speed

etc...

As far as flying a straight in approach at a constant 70 kts, that probably isn't needed on a 10 mile final but some personal limits are needed to ensure a stabilized approach before arriving at the numbers. Also, the article mentions doing it in jets and that is an entirely different animal as the much larger mass and energy needs to be managed more carefully when trying to dissipate energy as there is not a big prop spinning out front to slow you down, especially if you have a CS prop.

I get the sense that he is discussing the typical bomber pattern that the FAA currently favors. He suggests that dragging a 150 down a 3 mile final at a single speed is a waste of time. He suggests that as long as you are at the proper speed crossing the threshold, you should be able to fly the pattern at whatever speed is required to keep the pattern freed up. Make a fast (or tight) pattern - but have the skill to be on speed at the T.

You are over thinking what the author said, Glen.

All he is saying is it makes no sense to fly a long straight in approach at 70 knots just to be stabilized.

A stabile approach is a good idea IFR, you don't want to be changing anything the last few minutes. VFR is different, keep it rolling the guys behind you will appreciate it. But know how to reduce to landing speed before going into flare.

3? is a good glide any time. Steeper is ok if speed can be controlled. But dragging it in at 1-2 degrees is not so good. Being close to the ground when it is not necessary always runs the risk meter up.

David, I agree.

I felt the author of the article was "under thinking" his topic. Based on the text and diagram, I feel he was not giving a usable picture for the reader.

As a matter of fact, your short comment on the pros/cons is more valuable to a reader.

BTW: it's interesting to note, if you fly the patter like many (?) CFI's describe, "flaps abeam the numbers, turn when the threshold is behind you at a 45, ..." Then a one mile pattern distance gives you a 3.2 degree decent angle from a 1000' pattern altitude. This reinforces the importance of a tight pattern.

Glen, were you ever a glider pilot? That discipline makes the pattern very clear and understandable. No confusion with a throttle.

David-aviator said:

You are over thinking what the author said, Glen.

All he is saying is it makes no sense to fly a long straight in approach at 70 knots just to be stabilized.

A stabile approach is a good idea IFR, you don't want to be changing anything the last few minutes. VFR is different, keep it rolling the guys behind you will appreciate it. But know how to reduce to landing speed before going into flare.

3° is a good glide any time. Steeper is ok if speed can be controlled. But dragging it in at 1-2 degrees is not so good. Being close to the ground when it is not necessary always runs the risk meter up.

Click to expand...

David, if my calculations are correct, 3 deg requires (is) a glide ratio of 19:1. And at a glide ratio of 8:1 the angle would be 7 deg. Mike taught me in transition training to fly a tight pattern and it was always within glide of the runway. In the context of this straight in with traffic, what is our best choice for managing the risk meter? Avoiding it by making more friendly pattern entry?

PS - I am not flying yet and was thinking about this as creating a glide cone of know distance and altitude over the airport for early flights.

Just wondering... With a 3 degree slope from 1000' altitude, starting far enough back that if you kept that slope you'd land on the numbers, would you make the airport if your engine quit?

Not unless your airplane has a very high glide ratio - greater than 19 to 1.

If your plane has a 10 to 1 glide ratio. for example, that would be a 5.7 degree glide slope.

Dave

slight drift

I will try to include the slope in my comments to honor the OP. I was approaching Cable airport last week in California. It is complicated because the controller wants you to avoid Ontario airspace. Long story short, if you follow directions... you end up pointing at the westbound runway with a less than optimum slope angle. I reported on the radio and was immediately "chewed out" by a voice on unicom. He was upset that I was straight in. I had actually not even announced my pattern intentions, just position. A student was holding at the departure end in a Cessna. I ended up doing an overhead "break" to the left to enter downwind, just above the waiting Cessna. I suspect the CFI and even younger student were not sure what to do. My goal is to live through an engine failure. I have survived one aircraft on fire with heavy cockpit smoke, one antique that simply went quiet, a hot air balloon into the trees when options got limited and a two stroke powered parachute that become an unpowered parachute over an extinct volcano. Angle of approach is important, surely. Life is more important. If you do your best to keep your RV in a position and condition where it won't kill you, you get your money's worth. You get tomorrow.

300 feet vertically in 6076 feet/NM is just about 20:1, agreed with above calculation.

I'm a glider CFI and heavy jet type. Had a Pitts for years.

The most efficient pattern to land the most somewhat similar planes is a single turn from a perch through base to final. It's great if there is a geographic reference. Don't forget you are belly up to NORDO straight-ins. You can glide if need be if that point is not too wide or you too low.

Since it quickly stacks up on downwind past the 45 AIM entry, it upsets some. I'm also mil, so the overhead is fine for me to use or space for those in the break. Sure, some may carry through or go around for spacing, but the max landing flow can be maintained.

Departures need to be as pattern aware as arrivals- that is why a spotter like at big fly-ins adds a ton of safety.

The 3 degree final is fine, but as above, steeper to a point for your glide is safer, as long as it doesn't raise the collision risk.

Flexibility and currency in type are the keys, good comms help.

It depends!

Landing discussion starts on page 225:

https://drive.google.com/file/d/0B8EIT6g2n8o_N3EwV3NCWUhmMU0/view?usp=sharing

Consideration is given for use of various glide angles as well as rules of thumb for computing required VVI. Different types of patterns are discussed, Em (energy management--i.e., glide performance) considerations are included as well as example stabilized approach criteria as would apply to an RV-type.

Emergency landing discussion begins on page 292.

Instrument approach discussion is in the all-weather operation section on page 312.

Fly safe,

Vac

I was just thinking about this a couple nights ago while night flying. If I actually used the VASI, which I presume is set at a 3-degree glide slope, there is no way I would make the runway without power. Even my -9 doesn't glide that well. Thus, even (and perhaps especially) at night I make sure I'm well above the glide slope. (VFR, of course.)

NORDO straight-in!?!?!?

moosepileit said:

The most efficient pattern to land the most somewhat similar planes is a single turn from a perch through base to final. It's great if there is a geographic reference. Don't forget you are belly up to NORDO straight-ins. You can glide if need be if that point is not too wide or you too low.

.

Click to expand...

I totally agree with the moosepileit's pattern suggestion, that's my standard pattern, with the addition of a stabilized downwind leg to the perch.
In addition to any geographic reference, its really great if the runway is not moving

Just the mere mention of a NORDO straight-in made me bristle. Very poor judgment for any pilot to do that, except at a private strip or situation that they are intimately aware of.

Think about it: You may not know what the wind is, you have no idea what the conditions are at the field, whether there are airplanes in the pattern, etc.

Sound NORDO procedure at uncontrolled airport would be to insert yourself gently into the situation, not just come bombing in on final with no clue of what else is going on.
How about: overfly the field at 1500 AGL, look at the wind sock, look at who is in the run-up area, make sure there's no cows on the runway, descend on an extended upwind and crosswind, watching for anyone inbound on the 45, and once you start turning downwind, you sure better be looking everywhere, because you don't know where anyone else is.

But I suppose there are pilots out there with such poor judgement that they would do a NORDO straight-in, so the rest of us need to watch out for them.

scsmith said:

Just the mere mention of a NORDO straight-in made me bristle. Very poor judgment for any pilot to do that, except at a private strip or situation that they are intimately aware of.
...
But I suppose there are pilots out there with such poor judgement that they would do a NORDO straight-in, so the rest of us need to watch out for them.

Click to expand...

One could argue that intentionally flying NORDO into a busy field, regardless of technique, is maybe not sound judgment. Handhelds are cheap, in airplane units.

scsmith said:

I totally agree with the moosepileit's pattern suggestion, that's my standard pattern, with the addition of a stabilized downwind leg to the perch.
In addition to any geographic reference, its really great if the runway is not moving

Just the mere mention of a NORDO straight-in made me bristle. Very poor judgment for any pilot to do that, except at a private strip or situation that they are intimately aware of.

Think about it: You may not know what the wind is, you have no idea what the conditions are at the field, whether there are airplanes in the pattern, etc.

Sound NORDO procedure at uncontrolled airport would be to insert yourself gently into the situation, not just come bombing in on final with no clue of what else is going on.
How about: overfly the field at 1500 AGL, look at the wind sock, look at who is in the run-up area, make sure there's no cows on the runway, descend on an extended upwind and crosswind, watching for anyone inbound on the 45, and once you start turning downwind, you sure better be looking everywhere, because you don't know where anyone else is.

But I suppose there are pilots out there with such poor judgement that they would do a NORDO straight-in, so the rest of us need to watch out for them.

Click to expand...

Totally agree with you that intentional NORDO straight in at any field is less than great judgement.

However - how many of us have ever dialed in the wrong frequency? Or had a bad antenna wire? Broken headset mic? The are reasons people are NORDO other than doing so intentionally - and we always have to assume that they might be out there - because they very well might be us....

The only time I see that I'm right on the glide slope is short final. Any farther out and I'm way above the glide slope. VFR of course and enjoying it....

When I first started flying the RV-6A...

I was a bit disconcerted at the landing approach profile that seemed to work vs what the VASI was telling me. Now it's all part of the game; I've gotten completely accustomed to watching the VASI lights go from 4 whites as I turn final to 4 reds as I cross the threshold and kiss the mains on the numbers.

Two whites and 2 reds on the VASI at a quarter-mile and 70 mph IAS means power is needed NOW to stay out of the REIL hardware - or worse. These planes glide like a manhole cover with full flaps out. You simply get used to it and plan accordingly.

What that translates into for glide slope, I'm not sure. But I'm pretty sure a 3-degree approach is not part of a stabilized, power-off approach for my RV, Glen. Not physically possible with flaps out.

-Stormy

PAPI

Bill Boyd said:

I was a bit disconcerted at the landing approach profile that seemed to work vs what the VASI was telling me. Now it's all part of the game; I've gotten completely accustomed to watching the VASI lights go from 4 whites as I turn final to 4 reds as I cross the threshold and kiss the mains on the numbers.

Two whites and 2 reds on the VASI at a quarter-mile and 70 mph IAS means power is needed NOW to stay out of the REIL hardware - or worse. These planes glide like a manhole cover with full flaps out. You simply get used to it and plan accordingly.

What that translates into for glide slope, I'm not sure. But I'm pretty sure a 3-degree approach is not part of a stabilized, power-off approach for my RV, Glen. Not physically possible with flaps out.

-Stormy

Click to expand...

Sorry to be nitpicking, but it sounds like you're describing PAPI lights instead of VASI lights...

I agree that if the PAPI/VASI shows I'm "on slope" i better be on very short final or on an instrument approach.

My personal opinion is that the need for a "stabilized approach" is hogwash for single engine light aircraft flying VFR.

Skylor
RV-8

Bill Boyd said:

... at a quarter-mile and 70 mph IAS means power is needed NOW to stay out of the REIL hardware - or worse. These planes glide like a manhole cover with full flaps out. I'm pretty sure a 3-degree approach is not part of a stabilized, power-off approach for my RV ...

Click to expand...

Like you, I'm at 60kts on short final and I've roughly calculated my "engine near idle" decent at 10+ degrees. I'm getting use to the AOA and what it's telling me. It's doesn't care about what my airspeed says