View Full Version : The ILS Approach

Global Pilot
30th Jan 2005, 16:32
Looking for some information on the differences between shooting an ILS approach in a helicopter versus a fixed wing aircraft. Also on any difficulties rotarcraft have performing an ILS at a busy international airport.

Any info for a dumb stupid ass fixed wing pilot would be really appreciated!

30th Jan 2005, 18:04
Biggest hassle is when helo drivers slow way down and chew up more airspace, stacking those starch-wings up behind you. Most ILS are shot at 130K+ by airplanes, so if you use 70 or 80 you really bog down the guys behind you. In an S-76, a 120knot ILS is a nice one, and you always have at least 1/2 mile to burn off the speed at the bottom. If ceiling is really at mins, and the ILS runway has only 1/2 mile to the ramp, then maybe slowing to 90 is better, but for big airports and average conditions, I shoot them at 120 knots.

Also, the higher speed makes it easier to track the beam, since a given bank angle error yields a fraction of the turn rate error, so you can catch heading drifts much faster. Also, the airspeed produces more ROD adjustment, since the power curve is steeper at 120, so plus or minus 5 knots is a fine glideslope adjustment.

30th Jan 2005, 19:08
Bad Nick, naughty Nick! All us QHIs spend hours nagging at pilots to control height or RoD with lever and here you are saying do it with cyclic - heresey! you'll be burned at the stake!!!

30th Jan 2005, 19:43
Global Pilot,

The big problem with Helis doing fast ILS approaches is that the speed has to be washed off at the bottom (we obviously can't land at fixed wing speeds, especially if there are skids rather than wheels fitted) which can put the aircraft above the glideslope or even back into cloud if the pilot isn't careful, due to flare effects tending to convert speed to height. Also, in extremely poor conditions, the single pilot has to go from instruments to flying at very low speed or to a hover with marginal visual cues, a "third dimension" that isn't necessary in fixed wing (once the aircraft has touched down on the runway it's a 2D environment).

We are based at a busy airport and often get asked to make "best speed". 130 kts is good for ATC but it does mean that the gear can't go down until late on the approach. Personally, I use the airspeed hold and control the airspeed with the coolie hat and let the aircraft make its own arrangements - it does it so much better than me!

I then "beep" the speed back to get below gear limiting speed and if the weather is right on limits I bring it back to 75 or 80kts to make life a little less hectic over the runway.

Geoff Williams
30th Jan 2005, 20:04
I'm with crab on this one Nick.

Control the path on the glide slope with the collective. Especially so with a attitude retention system such as an un-coupled approach with an A/P equipped aircraft.

Also lets remember the Regulations re Speed restrictions. As a helicopter is classified as a Cat A for speeds, a Cat A speed range on final approach is 70 to 100 knots. This still allows for up to 150 knots on the intial and intermediate segments of the approach.

30th Jan 2005, 20:53
Agree with Geoff regards the CAT A speed restrictions ... but ... I found that if you can shoot the approach faster then the ATC, especially at Sydney and Canberra really appreciate it. Have shot them at 170 in the Seahawk and found that as long as you're slowing down by about 2 to 3 miles on finals, then the maintenance of the glideslope is pretty easy. Not advocating busting the rules at all but I find the CAT A limitations these days a little frustrating....worked well in the days of Hueys though.

Have found that at the higher speeds, Nick's technique provides more accurate glideslope control. Maybe it's a Sikorsky thing.

30th Jan 2005, 22:01
If you start altering your airspeed on the ILS, regardless of what cat. approach your flying, doesn't this mess up your timing to your MAP should you have a glideslope failure? or do you maintain your KIAS after the FAF until DA/MDA?

Camp Freddie
30th Jan 2005, 22:30
Well I guess the bottom line is whatever works for you.

I personally on the S76 fly the whole approach on the cyclic use the trim release (not the fine trim) for adjustments, as I like Nick find that the delay if you use the lever is too long.

I only touch the lever if the speed gets too far out of line from your target i.e. more than 125, or less than 115.

however typically I give the lever a single little nudge down at about 1000' which allows for the increasing air density as you descend which if you didnt do would mean that your speed would be too high at the bottom.

as for the timing by changing speeds it is obviously important if you are flying an NDB from a locator beacon (outer marker), but where the MAP is at the beacon on the airfield or you are flying the ILS down to 200' and as your speed will be within the typical IR limits +/- 5 kts anyway who cares about that ?
(I guess someone will quote from pans ops now)



30th Jan 2005, 23:30
We always learn things!

Goeff and Ogsplash - Helicopters are ALWAYS Cat A on the approach plate, guys, no matter what speed you fly. That is because you don't have a 1.3 Vso (unless I forgot and left the wings on my helo). The limits to maneuver are meaningless to a direct lift aircraft that is at its best maneuver condition when a starch-wing is teetering at the edge of control. I agree with you Ogsplash, the slow down usually starts much earlier, since you usually break out at 500 or 700 feet, where you are miles away from the turnoff.

Crab - 5 knots of speed at 130 is worth the entire ILS ROD, so a few knots is powerful, and easy. If you juggle the collective, be my guest. I use the first 4 knots for altitude, then back off a little collective.

Lightening_Boy - a few seconds difference makes no real problem, really. If your glideslope fails, you are non=precision, anyway.

Gear speed is a real concern, I agree. If you can't drop your wheels at 130, you are perhaps flying the wrong type, since an S-76 is 130 gear down speed. I do agree that I want the wheels down at the FAF, and if your gear speed is much less, be at the gear speed. It is tough enough at the bottom without hearing that terrible scraping sound!

It is fairly easy to stop a 130 knot helo when at 1/4 mile from the threshold, and you have a further 4000 feet to the tower/terminal, (giving you the much better part of a mile, if you are only visual just as you hit minumums). This uses about 7 degrees nose up attitude for most helos, an easy thing visually. If you can't do this, can I suggest perhaps dentistry? ;-)

Seriously, I use 125 for most ILS and find it very easy, but if you are right at mins, and it is a small airport, and its night, I get down to perhaps 90. I flew several hundred approaches to zero zero during a test program once, and found the precision of localizer glideslope retention much better at the higher speed. The turn rate is based on v squared, so if you are at 70 you have almost 4 times the turn rate for 1 degree of bank as you do at 125. This means your flying has to be more precise to achieve the same nav accuracy, or stated another way, your precious workload is being used to keep sharp bank when it could be helping you maintain other awareness.

Gomer Pylot
31st Jan 2005, 00:22
Jacking the collective up and down is an easy way to get an unstabilized approach. I also set power and leave it there, and control the glideslope with airspeed. One thing to recall (FAA regs, others I don't know) is that if you reduce the published visibility by 1/2 then you must be at or below 90 kts before the MAP. I often fly at higher speeds and then start reducing airspeed at about 200', but if the weather is really down, and visibility is below 1/2 mile, then the airspeed is going to be 90 or less just about all the way, and screw any fixed-wing behind me. Fortunately I don't have this problem often, and I'm usually the only aircraft on the ILS anyway. But if I have to go to my alternate, which may be a large metropolitan airport, then I'll do what I need to do. We try to accommodate others when we can.

I never time an ILS. If the glideslope fails on the way in, then it's a missed approach and rebrief for the localizer. One brief, one approach, period.

31st Jan 2005, 02:51
Gomer Pylot

"I never time an ILS. If the glideslope fails on the way in, then it's a missed approach and rebrief for the localizer. One brief, one approach, period."

Just out of curiousity, why is that? Wouldn't it be just as easy to brief the approach with the MDA as well and just hit the timer at the FAF?

BTW, I'm no expert, sitting my IR next week hopefully!!!!

helmet fire
31st Jan 2005, 03:45
Ogsplash and Geoff are referring to the Oz regs which is supposedly a pans ops reflection, but I must admit I interpret them differently. The wording is from AIP, ENR 1.5 - 2 para 1.3.1 (b):
"where helicopters are operated similarly to aeroplanes, they may be classified as CAT A"

I read the critical word as "may", not must, shall, or will. In otherwords, when doing an instrument approach such as the ILS in the 212, then CAT A is beaut. But in the BK117, when I want to do 120 kias down finals (which, like Nick I also prefer) then I simply use CAT B minima requirements. If I feel I need the CAT A minima (almost never different in Oz to CAT B) then I limit finals speed to 100. I think this is reasonable given the wording that says I "may" operate as CAT A.

As for attitude Vs collective for glideslope, it depends on the machine/situation. Using attitude to correct for glideslope in the 212 can lead to VNE, and using collective to come up at 145kias in the BK can lead to overtorques!! Nick's 4 kts is a good idea, and I'll try it next time - thanks.

In answer to the original question, I think it is easier to shoot an ILS in a helicopter than a fixed wing, and I think from the subsequent discussion you can see that it is far more flexible with far more options.

31st Jan 2005, 03:50
Control the path on the glide slope with the collective
Which is all well and good if you're flying manually, but the autopilot does it with cyclic. Well ours does. Are there any autopilots that control height with collective?

31st Jan 2005, 07:26
Mighty Gem, yes there are; those that are 4 axes. On the 155 the collective is coupled when using vertical functions on their own, but with the IAS below 60 kts (ie ALT, V/S or G/S ) or when the IAS and a vertical function are coupled together. If above 60 kts and a vertical funtion is coupled but not the IAS, then it uses the cyclic to control that function, and effectively the collective becomes a speed controller.

When fully coupled on an ILS it has to be seen to be believed; you can merrily beep the IAS from 165 to 30 and then back and the needles don't budge at all. It will then take you all the way down to 25 ft and 30 kts down the centre of the runway, hands off (well, lightly guarding the controls, perhaps!) On top of that, it has no gear limiting speed, which is a bonus.

I'm surprised by how many people advocate glideslope control using cyclic, especially the 76 drivers; I always thought it was delightful to hand fly accurate ILS' with its PBA. An accurately trimmed aircraft in smooth conditions needs very little cyclic input and just small, smooth, collective inputs, usually. If, however, you then factor in a bumpy approach, what are you using the controls for (those that advocate cyclic for glideslope)? Do you still keep the glideslope with cyclic, but accept bigger speed variations, or do you adjust the collective to reduce the speed variations, or do you move everything and adjust both speed and glideslope with a combination of both inputs? If you stick to the primary effects of control, the principle doesn't change; you still maintain the IAS with cyclic and the glideslope with collective, you just need more frequent and larger inputs.

One advantage of our flexibility with IAS is that by keeping it high in the initial stages of the approach we can minimise the wind's drift, then by reducing it in the final stages we can remain within the rapidly constricting cone more easily.

Was once asked by ATC to "slow down" behind an Airbus A320, which brought a smile to my face.

31st Jan 2005, 08:57
I'm totally with Nick Lappos on this one. Every IFR helo I've flown is easier to fly the approach with the stick. Set a ball park power setting as the glide slope comes in and then use the stick to the bottom. I've used this on S61, S76, AS332, AS365 and the355. All behave the same when using this technique.:)

John Eacott
31st Jan 2005, 09:11
My preference is Nick's technique, especially in the very stable S76. Although I hear that dropping the airbrakes at the OM is pretty good for final speed control ;)

I hoped to try a couple of ideas this afternoon, but the IP with me thought it more fun to take off the pri hyd (no T/R assist), then the No 1 engine, then a running landing :rolleyes: At least the 109 Power with the new tail rotor blades is quite benign hydraulics off, compared to the "old" blades :)

Collective Bias
31st Jan 2005, 20:52
I am basicly a S76 driver and I always prefer controlling glideslope with cyclic. Way back in my basic IR I was thought to do it with collective, but soon found out cyclic worked better for me. And actually, when flying as an instrument instructor and see pilot hand fly an ILS with collective, they normally do a much better job when doing it again with fixed power setting. It is just one less thing to work with in IMC, and doing it in IMC is really the diffrence.

On the S76 35-40% tq for ILS is a good baseline that works for most of the time, will give 120 with gear down.

An S76 with Phase 3 is the only one I find it better to adjust glideslope with collective since it is so stable in attitude and speed.

To be honest, I do not think a 4 axis AP flies glideslope adjustments with collective, it maintains airspeed with collective (or slows it down in decel mode) and follow the glideslope with cyclic (pitch actuator). Somebody might be able to confirm/correct this.

To me it seems that most Bell pilots want to fly the glideslope with cyclic. Also for UK pilots it seems to be the prefered choice. Have no idea why in both cases.

Anyway whatever works for the individual with the least workload must be accepable:ok:

CB (hiding for flak).

Gomer Pylot
31st Jan 2005, 22:06
Lightning, it's a different approach, with different minima, and different requirements. Trying to salvage an approach when things start going wrong can be very dangerous, and I want to live to fly again.

31st Jan 2005, 22:50
Thanks for that, 212Man.

I was told tonight(during the IF phase of my 6 monthly check), that here in the UK you should use the collective. Certainly during an IRT as using the cyclic will put you outside of the +/- limits for speed, resulting in a fail.

helmet fire
31st Jan 2005, 23:04
Flying the ILS with cyclic in Oz also has another ramification: and adjustment of 10 kias, or 10% which ever is less, shall be notified to ATC. Also, I wonder what the efeects on preceeding/following traffic would be, but I suspect it is minimal given seperation standards.

Collective Bias, I suspect your comment of most Bell pilots flying the cyclic could be reworded, as I find it is most Jetranger pilots - but not Huey pilots. They tend to get in the habit of setting top of the green and flying altitude with cyclic in the cruise, whereas in the Hueys (except 412), doing this would result in a significant VNE exceedance. Given alot of guys have flown jetranger first, it is a habit that needs to be sorted out in the huey transition.

1st Feb 2005, 05:37
Nick, I think you are wrong about helicopters being cat A at any speed. The airspeed you are flying when you arrive at the missed approach point determins the approach catagory and minimums used. If you are at 125 knots at the missed approach point you are a Cat C aircraft. Higher speeds produce a larger turn radius and reduce the climb gradient. Faster aircraft need more protected airspace and have higher approach minimums.

1st Feb 2005, 08:14
JHR: I think Nick is right, Helicopters are always CAT A as the category is based on stall speeds plus safety margins.

1st Feb 2005, 09:44
Collective Bias,
I can only speak of one 4 axes system with any knowledge, but the one I'm familiar with uses collective for Height/Vertical speed and cyclic for IAS.

In fact, in the cruise at max power it will use cyclic if required to avoid exceeding power limits, but that doesn't apply to an ILS.

Mighty Gem, you are right; it is frowned upon by UK examiners, part of the skill being tested is the ability to maintain datums accurately and that is not just the ILS needles, it's the IAS too.

1st Feb 2005, 11:15

Does not your own product, the Black Hawk, come with a Command Instrument System that uses collective for the G/S?

Incidentally it is a great system that will allow you to fly the nicest ILS you are likely to, uncoupled.

I have always found using collective the simplest control for G/S as it controls the RoD and therefore when flying a non precision approach the same technique can be used. Flying approaches at a faster speed can still accomplished using this technique, especially with even the simplest of autopilots - me.

Call me crazy but being a simple guy it allows me to keep everything simple. Left hand angle, right hand speed and direction, footrests for the ball thing.

It even works when I'm not instrument flying and just wanting to land.

My students, who are generally simpler than me also seem to manage it too.

1st Feb 2005, 14:19
I'm with JHR on helos not being Cat A at any speed. Reference is PANSOPS Vol I, Pt 11, Ch 1:

"When helicopters use procedure designed for Cat A aeroplanes the following operational constraints must be considered:
a) Range of Final Approach Speeds
b) Rate of descent after fixes.

Ch 2:
"Final Approach Speeds Cat A 70/100, Cat H 60/90"

That deals with the low end of speeds, there is no quote for helo speeds which match those of higher FW Categories, but it seems logical that helos should conform to the appropriate Speed Category.

1st Feb 2005, 14:54

How the CIS flys the procedure is not how a pilot does, the CIS is an autopilot with a "Meat Servo." I know, I was the pilot who developed the CIS on the Hawk.

That being said, I think you are inferring there is a "right" and a "wrong" way to fly an ILS. I disagree. Have fun your way, I certainly don't mind.

Hard working pilots who lose situational awareness are the ones who die. I suggest if you have two ways to do something in the air, during a critical procedure, and one way is easier and the other way is harder (but Her Majesty's Helicopter Guide/George Bush's Helicopter Guide says it is "better"), please do it the easy way, so you have more pilot mental capacity at the bottom of the approach, when you need it most.

1st Feb 2005, 17:10
Under FAA and UK CAA (JAA) regulations helicopters are allowed to fly approaches using Category A minimums.

The following is the FAA regulation:

10-1-2. Helicopter Instrument Approaches

a. Helicopters are capable of flying any published 14 CFR Part 97, Standard Instrument Approach Procedures (SIAPs), for which they are properly equipped, subject to the following limitations and conditions:

1. Helicopters flying conventional (non-Copter) SIAPs may reduce the visibility minima to not less than one half the published Category A landing visibility minima, or 1/4 statue mile visibility/1200 RVR, whichever is greater. No reduction in MDA/DA is permitted. The reference for this is 14 CFR Section 97.3, Symbols and Terms used in Procedures, (d-1). The helicopter may initiate the final approach segment at speeds up to the upper limit of the highest approach category authorized by the procedure, but must be slowed to no more than
90 KIAS at the missed approach point (MAP) in order to apply the visibility reduction. Pilots are cautioned that such a decelerating approach may make early identification of wind shear on the approach path difficult or impossible. If required, use the Inoperative Components and Visual Aids Table provided in the front cover of the U.S. Terminal Procedures Volume to derive the Category A minima before applying the 14 CFR Section 97.3(d-1) rule.

FAA AIM extract (http://www.faa.gov/ATPubs/AIM/Chap10/aim1001.html#10-1-2)

1st Feb 2005, 19:30
Without reading the technical details, I'm not sure how one could tell which control is controlling what, because everything affects everything. Moving the collective can change the airspeed or rate of descent, as can the cyclic. Everything is dependent on everything else, and none of it is independent. The cyclic has to be moved all the time in response to changes in wind, power, etc, and thus it's easier for me to leave the collective alone and use the cyclic, which is going to have to be moved in any case, for controlling as much as possible. When you're flying, you move what you want when you want. IMO this has always been a silly argument.

1st Feb 2005, 21:00
Approach categories:
To paraphrase the AIP (CAN) the visual Maneuvering Area is determined by drawing arcs centered on each runway threshold and joining those arcs with tangent lines. The arcs are related to aircraft categories: A 1.3 NM; B 1.5NM; C 1.7NM; D 2.3 NM; E 4.5 NM. Staying within the prescribed arc for your speed category will insure a minimum obstacle clearance of 300 feet.

A helicopter is considered to be in category A [speed up to 90 knots] for all approaches. How ever if maneuvering for a circling approach at speeds above 90 knots then the appropriate circling minima for the speed category should be applied to ensure obstacle clearance. i.e. if maneuvering at 125 knots then the minima associated for a category C aircraft should be applied.

Flying ILS approaches:

When I was an IFR instructor pilot I encouraged pilots to maintain glide slope (GS) with collective. Reason; it was simple, effective and it gave them something to work with.

A Flight director in either FW or RW flies the GS using pitch, power {collective or throttles} is used to control airspeed.

In reality flying a glide slope is a combination of both pitch an attitude. When an immediate rectification is required pitch (cyclic) is the most effective; for minor trend variations collective would be more appropriate.

I use a combination of both when on the GS. A 3-degree glide slope is a decent of 318 feet per nautical mile. A good rule of thumb to determine the rate of decent required to maintain a 3 degree glide slope is:
AS/2 * 10= ROD, example: 120knots/2 *10= 600 ft per min..

I would then adjust attitude and power to maintain AS and ROD.

donut king
2nd Feb 2005, 00:22
The Canadian IPM has: collective= altitude control, cyclic= airspeed control, and t/r pedals= trim.

Nick L., is that not the reason for the PBA.... maintains attitude thereby maintaining airspeed during collective inputs???

I was told that the DAFCS computers ( HP's/ AP's) substitute for the PBA action during the ILS for example.

I am not disagreeing with anyone here. I just want to know how the a/c systems( S76) are designed to be used.

As well, during my instrument training years ago, I was taught that chasing altitude with cyclic is a big no-no.

Anyone else( from Canadan training background) care to add.



2nd Feb 2005, 02:28
Woolf, the paragraph's from the US TERPS explain the application of approach catagories. FAR 97 does authorize helicopters to use Cat A minimums, if you look at "copter only" procedures the max airspeed is 90 knots. The speed limit is not because of stall speed. It's a limit because of the size of the airspace protected for the approach procedure.


212. APPROACH CATEGORIES (CAT). Aircraft performance differences have an effect on the airspace and visibility needed to perform certain maneuvers. Because of these differences, aircraft manufacturer/operational directives assign an alphabetical category to each aircraft so that the appropriate obstacle clearance areas and landing and departure minimums can be established in accordance with the criteria in this order. The categories used and referenced throughout this order are Category A, B, C, D, and/or E. Aircraft categories are defined in Part 97.
213. APPROACH CATEGORY APPLICATION. The approach category operating characteristics must be used to determine turning radii minimums and obstacle clearance areas for circling and missed approaches.

2nd Feb 2005, 12:39

The Catagory is tied to the stall speed, directly, since the approach speed, which deternines the catagory, is based on 1.3Vso.

Helicopters have no stall speed, and they can decel independant of their descent angle (they are direct lift machines) thus the Catagory a helo uses is always Catagory A. The exception is where the speed restriction is declared as 90 knots (or 70 for designated GPS approaches), sometimes imposed for copter only approaches, and when you halve the visibility.

2nd Feb 2005, 17:17
In the below example if doing an approach to rwy 25 at YGR the MDA would be 300 feet. If doing the approach to runway 25 with the intention of circling for rwy 16 or 07 your MDA would be 540 feet if your manuvering speed was up to 120 knots. Should the pilot choose to manuever at 125 knots then the MDA would be 560 feet to comply with obstacle clearance requirements.


2nd Feb 2005, 20:39
Straight-in and circling approaches are not the same thing. A helicopter is always Cat A for a straight-in approach, but for circling the speed used in the circling maneuver applies. But to me this is a moot point, because why would you ever want to circle to land at more than 90 kts in a helicopter? In fact, why would you circle to land at all, unless instructed specifically to do so by the tower, or if flying an approach that is specifically a circling approach? We fly a straight-in approach, and then perhaps turn into the wind while air-taxiing for the final touchdown, while over the runways or ramp, but this isn't a circling maneuver.

2nd Feb 2005, 21:45
GLSNightPilot I agree with you.

The point I was trying to make is that; if for some reason you have to circle for a runway[especially at night] other than the one that you've flown the approach to because of wind, weather, ATC then in order to meet obstacle clearance requirements you have to maintain the minimum altitude appropriate for the speed flown.

As an aircraft doubles its speed the turning radius quadrupules.

helmet fire
3rd Feb 2005, 12:48
IHL, the speed analogy hits the nail on the head (though our deceleration is not limited by stall), and that is why I adjust minima (straight in or circling) to suit my selection of finals speed. More importantly, I select a finals speed to be under the limit of the minima I anticipate requiring. Though I see Nick's point of always being CAT A, I prefer a more conservative interpretation of our Oz regs: the finals speed determines minima at the missed approach point/DH.

Shawn Coyle
5th Feb 2005, 17:05
Where are the words that say "Helicopters are always Cat A regardless of approach speed."?
From the number of times I've heard the opposite, there are a lot of folks who don't know that, and we need to make sure we get the word out.

5th Feb 2005, 19:35
The important thing for this speed question (from a legal standpoint) is that the Catagory speed for a helicopter has NOTHING to do with your speed on approach, it is, by FAR, Catagory A for airplane instrument procedures:

"(d-1) Copter procedures means helicopter procedures, with applicable
minimums as prescribed in Sec. 97.35 of this part. Helicopters may also
use other procedures prescribed in Subpart C of this part and may use
the Category A minimum descent altitude (MDA) or decision height (DH).
The required visibility minimum may be reduced to one-half the published
visibility minimum for Category A aircraft, but in no case may it be
reduced to less than one-quarter mile or 1,200 feet RVR."

Let me be very specific. If I have a 156 knot helicopter, and I fly an ILS at 156 knots, I use Catagory A mins and I would be legal. It is also quite possible that an ILS to JFK or Heathrow at this speed would allow me to break out at mins at 156 knots, slow to a hover, and then have to reaccelerate to get to the ramp.

Note that several types of Copter procedures exist, and they specify the maximum speed on approach, and have no Catagories. Of special note are the new GPS 70 knot "T" procedures, which must be flown at 70, because you will not fit around the T if you are going very much faster.

From a non-legal standpoint, the idea of being slower at night, or when the wx is poor, or when you feel it is right, is certainly good sound airmanship!

8th Feb 2005, 19:46

The current US Airmans Information Manual helps clear up the issue. The entire TERPS manual is incorporated into the current FAR 97. Paragraph 212 & 213 detail how the aircraft approach catagories are used to determin obstacle clearance during approach construction. It's certainly possible to fly the ILS to JFK at 150 Kts, land and have to accellerate to get to the ramp. It's done every day by 747's and other large aircraft. When you are flying the approach to BFE and the straight in CAT B minimum is higher than the CAT A minimum I think you need to concider what you may run into during the missed approach segment if you fly the higher airspeed.

10-1-2. Helicopter Instrument Approaches

a. Helicopters are capable of flying any published 14 CFR Part 97, Standard Instrument Approach Procedures (SIAPs), for which they are properly equipped, subject to the following limitations and conditions:

1. Helicopters flying conventional (non-Copter) SIAPs may reduce the visibility minima to not less than one half the published Category A landing visibility minima, or 1/4 statue mile visibility/1200 RVR, whichever is greater. No reduction in MDA/DA is permitted. The reference for this is 14 CFR Section 97.3, Symbols and Terms used in Procedures, (d-1). The helicopter may initiate the final approach segment at speeds up to the upper limit of the highest approach category authorized by the procedure, but must be slowed to no more than
90 KIAS at the missed approach point (MAP) in order to apply the visibility reduction. Pilots are cautioned that such a decelerating approach may make early identification of wind shear on the approach path difficult or impossible. If required, use the Inoperative Components and Visual Aids Table provided in the front cover of the U.S. Terminal Procedures Volume to derive the Category A minima before applying the 14 CFR Section 97.3(d-1) rule.

2. Helicopters flying Copter SIAPs may use the published minima, with no reductions allowed. The maximum airspeed is 90 KIAS on any segment of the approach or missed approach.

3. Helicopters flying GPS Copter SIAPs must limit airspeed to
90 KIAS or less when flying any segment of the procedure, except speeds must be limited to no more than 70 KIAS on the final and missed approach segments. Military GPS Copter SIAPs are limited to no more than 90 KIAS throughout the procedure. If annotated, holding may also be limited to no more than 70 KIAS. Use the published minima, no reductions allowed.



Bomber ARIS
8th Feb 2005, 20:14
What is wrong with the world.

Why are we discussing the protected airspace in the event of a go-around, when, as helicopter pilots, we "should" never even have to consider this event.

I want zero/zero approaches. I want them now. I want to fly the glide at max continous Q, slowing to 50 at 4 miles if wx warrants, and then land - EVERY TIME. I'm fed up of pretending my aircraft is an aeroplane.

I dream of the possible - when will the rest of the world join me??

(Dontcha love red wine....specially the second bottle............:zzz: )

8th Feb 2005, 20:55
It's possible right now. All it takes to make it happen is money and moving a few layers of bureaucracy.

8th Feb 2005, 22:10

Thanks for that, it does clear it up!


Shawn Coyle
12th Feb 2005, 07:28
Bomber Aris:
I agree. We should be looking for technology to unlock our potential.
I was lucky enough to fly approaches to a hover with Nick several (i.e too many) years ago, and was quite impressed. We have the technology, but not the political will.
My only concern with a decelerating approach to a low vis / ceiling is that we're going to need to have guidance down to the ground, as there will be a point on the approach where even a Category A helicopter will be committed to land if an engine fails. But given the state of Differential GPS, this should not be a difficult thing to do.
The real question is why don't we have it in work now?
Ask the FAA.
Ask HAI.
Ask AHS.
Ask AOPA (well, maybe not them).
Ask the EMS people.
Ask the military (by the way, we've had man portable ILS systems since the early '70s- ever see one in use in the military?)

12th Feb 2005, 11:38
OK, so assume we're making the rules now for virtually zero/zero (let's say 100m vis 50ft cloud base) approaches. What are the criteria going to be? Let's assume ILS equipped field first.

What tolerence of horizontal positioning (in terms of metres, say) on the ILS LOC and G/S is currently assumed to be reasonable? And vertical, from the G/S? Assume at 200ft. Obviously DME will back up horiz and altimeter/RadAlt the vertical. Presumably as the cone narrows towards the bottom the accuracy of the kit increases, if not the pilot. Do we need Diff GPS for greater accuracy/back up?

Is this a limitation or is the biggest deal one of speed of transition from IF to visual required at v low level?

Another point. Assuming a std 3 deg G/S flown at 70kts, which is prob about as slow as you'd want to go on an approach, nil wind vertical speed is about 350 ft/min. It interests me how slow in terms of mph familiar vertical speeds are - as a rough guide divide ft/min by 100 - so this gives you 3.5 mph. With wheels, what vertical impact speed is the gear designed to withstand? Could you just run on a S76 with no flare at 3.5 mph V/S? Thinking of emergency rather than routine you understand!

Guess Nick and Shawn should know some answers!

12th Feb 2005, 13:40
Having flown over 500 of these fully coupled DGPS approaches, to a hover, in conditions as difficult as 25 knots direct downwind, at angles as steep as 9 degrees, I can tll you that yesterday's autopilots are capable of keepng the aircraft within about 3 feet of the center of the beam, so nothing technically stops the effort. The current nav systems are capable of accuracies within 1 meter, without a ground station, and one inch with one.

Shawn tells it right, the failure of regulators to create the criteria, and the failure of operators to ask for it is where we have ground to a halt.

12th Feb 2005, 13:52
Interesting Nick, thanks.

So are you saying that the industry has not actually put a worked up proposal to the regulators? Guess this would be the first step - at least it would give the regulators something to work on, because I don't suppose they're going take the initiative themselves, which is no surprise.

12th Feb 2005, 15:52

You are right it is up to us, but the path is uphill!

It could start with an application from us, asking for approval for a particular system, but that would not get a new type of system approved, because it would be called a "special" and therefore a one-off. Each subsequent "special" would have to be approved from scratch at each location, as if the previous ones had never been done. This means special judgements, and no promise of capability until the procedure is done at each place.

To avoid that nonsense, we have to get a system (nav system, approach method, clear zones, geographic boundaries, obstruction clearances, publications) defined in the regulations as a normal one (like ILS, etc) so that rules would be codified and easily applied to each place.

New types of projects are hard to get approved right now. Since the FAA has embarked on a quest for a WAAS and a LAAS system approval, their funds and people are all tied up on these, neither of which has much applicability to us. They are not very useful to us because of the horribly bureaucratic means the FAA have applied to get these done, where the actual capability of the system is a fall-out, not a goal, of the system. (ie, the WAAS will get approved, we will tell you what the minumums are later, thank you very much. and oh, by the way, it will not be a good precision approach, but isn't that just too bad?)

The problem is simple, and we are bound to be miserable for a few more decades. What is the problem? The FAA owns the air, not us. If the Post Office invented email, we would be pasting stamps onto our monitors. If the Food and Drug Administration invented CAT scans, they would be housed inside old battleships. If the cell phone network were invented by the Feds, call phones would need small carts to drag the around. Innovation is brought about not by governments, but by enterprise, with operators and manufacturers all locked into commercial ventures to produce stuff and make it simple, safe, effective and operable.

In short, the FAA has exclusive rights to invent new procedures, and they couldn't find an inventor in the entire organization, with a microscope. No FAA guy will ever lose his job if he never invents another thing. Ergo, nothing will get done. Nothing, until we get the FAA to cede the creativity back to industry, and let us break loose with the technologies that have been around for a decade. The FAA would certainly have to ride shotgun on us, making sure it was safe. That is and should always be their job.

We are trying, I get fired up once per year! Maybe this thread will help.

Gomer Pylot
12th Feb 2005, 16:25
Bureaucracy is always resistant to change, and the operators are the ones who have to force it. But these approaches do require full autopilots, AFAIK, and those cost money to acquire and maintain. It seems there just isn't enough profit to be gained from operating at those conditions to justify paying for the additional equipment, at least in the opinion of the operators. If there were obvious profit to be made, they would be clamoring for the approaches. They aren't. And they aren't putting flight directors in helicopters, either. Some are taking out even the Phase 3 provisions from their S76s, because they don't want to maintain them, and don't want the pilots to become lazy by relying on electronics to do their jobs.

It continues to amaze me how idiots get to be in control of companies.

12th Feb 2005, 19:16
You hit the nail right on. The question is always "what more can I do, what will it cost to do it, and what can I charge for doing it?" Then we can price the extra business against the cost and decide. But until the procedure is a possibility we can't even whip out the calculator!

I think that we have seen the progression of helo ops toward full capability, just like airplanes went, but 40 years later. We actually debated if we should offer a VFR-only S-76!! We built and tested it, certified it, and sold ONE! Deice is the next boundary, and we will accept that as needed, ordinary and ho hum.

Then, I contend that full zero zero approach to helipads will be needed just to compete, probably in less than a decade. Yes, it will take a full autopilot, but it will help eliminate any reason to cancel, it will help eliminate CFIT and it will make helo ops as reliable as airplane ops. One accident for the fleet per decade would pay for every autopilot.

After we get zero-zero to helipads, I predict that we will have to develop zero-zero approach to anywhere (yes, anywhere) so that helo ops will be brought to a level of assurance and safety that makes them available everywhere.