Letters: April 2001

Budget GPS
I liked your article on GPS budget upgrades in the February issue. We have an Apollo loran-a real pain to operate-coupled to the autopilot in our 1978 A36 Bonanza.It does its job but I would love to upgrade. Which brings me to your article.

It seemed to me that you shorted Honeywell/Bendix/King a bit. I checked the internet (www.aircraftspruce.com) and they advertise a KLN 89B IFR for $2895 (maybe an overhauled unit, its hard to tell) and a KLN 90B overhaul for only $2595.

Why would these two units not be a better deal than some of the others you listed from Garmin and UPSAT/Apollo? I understand the comm issue, but if your radios are okay, why not try one of these two for one-half or one-third the price?

-Hugh A. Stafford
via e-mail

Actually, those arent bad deals for owners willing to buy used. We treated this subject in depth in the February 2000 issue of Aviation Consumer.

Jepp Takes Exception
Thank you for your review of Jeppesens FliteSchool vs. Kings multi-media course for the instrument knowledge test. We generally thought the information was fair and accurate.

We were concerned that readers might have been misdirected on a couple of points. With regard to the amount of screen space utilized by the program, we should point out that a 17-inch monitor set to 1280×1024 resolution is not a typical home computers setting.

On a more typical home computer setting of 800×600, FliteSchool fills the screen and even at higher resolutions, still uses most of the screen real estate. The expanded explanations, the online FAR/AIM, and the online textbook, which run in a Microsoft Internet Explorer browser window, can be sized to fill any size screen.

We also challenge the notion that bigger is better with regard to video on a computer. Jeppesens 320×240-pixel video window provides approximately the same resolution as VHS videotape.

Enlarging such a video to fill a large screen thats viewed only a foot away does not significantly increase information content, and we feel its somewhat disconcerting to look at an instructor this up-close and personal.

Jeppesen uses mostly instructor voice-overs with good quality still graphics. To keep the course on one CD, we use video sparingly where it communicates the point better. We believe a still graphic placed with well-formatted text looks sharper and conveys more information than graphics and text chroma-keyed behind an instructor in a video. Its misleading to suggest that a course is significantly richer in video content when most of the video content is the instructor in front of a still graphic.

When stating that the more expensive King course was the better value, we felt the reviewer missed the significance of the 900-page full color Guided Flight Discovery (GFD) textbook in Jeppesens kit.

That book quickly became an industry standard when it was published in 1998. Even though the FliteSchool software stands on its own, its designed to work effectively with the GFD textbook. Powerful training software is great, but Jeppesen considers a quality book an essential study tool as well.

FliteSchool was designed from the ground up to effectively use the computer medium to teach. Jeppesen designers believe it does this more effectively than simply transferring a video course, as good as the video may be, onto a computer.

-Anthony Werner
Senior Manager
Jeppesen Courseware Development

VGs vs. Climb Rate
I enjoyed your review of cabin-class piston Cessnas in the February issue but I did notice one quirk. Every time you mentioned vortex generator mods, you had no comment on the increased safety of lowering Vmc to or below stall, but rather harped repeatedly on the loss of single-engine rate of climb.

How good a rate of climb do you get in a Vmc rollover?I cannot imagine an engine-out situation where a slow, shallow, controllable descent would not be preferable to yaw-roll-spin-scream-die.

Probably the worst engine-out situation is losing one over the departure end of the runway at gross weight, high alpha, low speed and low altitude. Any other scenario gives you more time to control, confirm, cage, clean up and consider alternatives.

The 100 to 300 FPM single-engine ROCs given in piston twin POHs are best possible cases-sea level, standard day, test pilot, perfect technique, perfectly rigged and trimmed, strong new engine, fresh wax.

Any pilot who counts on achieving such a climb rate and flying away from a gross weight takeoff/climbout engine failure may be showing more ego than foresight, VGs or no VGs. As old author Leighton Collins used to say, A twin has two engines because sometimes, it needs two engines.Wishful thinking kills.

Perhaps a better plan in this situation is to maintain the lowest controllable airspeed and set her down more or less straight ahead, turning at most slightly to prang into the least deadly obstacles available.

If a forced landing is in the cards, VGs offer a lower minimum controllable airspeed and therefore a disproportionately lower impact energy and therefore a disproportionately higher survivability, all other things being equal.

-Art Legate
Colorado Springs, Colorado

We dont have a solid opinion on the subject of VGs. However, trying to get performance out of a twin that was never built into it in the first place is a ticket to disaster.

If a piston twin wont hold altitude on one engine, the only solution is to aim for something inexpensive and less resistant to impact than you. The most important rule is to keep the airplane right side up.

As you point out, lots of fatal accidents occur because the pilot got below Vmc and rolled it into the ground at a speed that would have allowed survival had he hit upright.

Our view is that if Vmc is below stall speed, the chances of keeping the airplane right side up are enhanced. With a lowered stall speed and Vmc, it stands to reason that its possible to impact the ground at a lower speed, thus improving survivability enormously.

A VG-equipped airplane may be an improvement when it comes to staying alive, but we havent seen any data one way or the other, thus we remain neutral.

Budget GPS and DME Arcs
Concerning the Budget GPS Upgrades article in the February 2001 issue of Aviation Consumer, I have the following comments concerning UPSATs GX-50 and GX-60 units.

If a user contemplates running many approaches at airports where VOR-DME Arc overlay approaches are used, then I would not recommend these two units.

I know that these types of approaches are not too common anymore but my home airport (KSPW), for example, has a total of 6 different DME Arc approaches – 4 of which have GPS overlays.

The GX-50 and GX-60 units have the various arc type GPS overlay approaches in their database, its just that they are cumbersome to use.

For some reason the pilot must also instruct the box which way he will need to turn (right or left) to intercept the arc on the approach.

If, for example, a pilot were to select a VOR-DME runway 30 approach at the KSPW airport via the MILSS intersection (IAF) and if he were approaching the airport from the east, he should not have to also instruct the box that he will need to turn left to intercept the arc.

These are the only IFR approach certified GPS units that I know of that cant use their internal computer to solve this obvious arc intercept turn direction question.

-Bill Hemme
Spencer, Iowa

We agree, the UPSAT designs to require a cumbersome logic to fly a DME arc. But, as you note, arcs are slowly passing into history.

All new GPS procedures being published by the FAA used the so-called terminal arrival area design, which consists of a T-shaped initial segment feeding into a straight final. At the ends of the Ts crossbars are the IAF/feeder fixes that render the DME arc obsolete.