Scan Polishing


read your article, “Polishing Your Scan: Our Top Five Tips” (December 2021), twice. As always, it was well-written and thoughtful. I have to say my experience with view-limiting devices seems to be the opposite of that suggested in the article. Compared to flying with a view-limiting device, I find it easier to maintain precise parameters when I’m actually in solid IFR or in a simulator/AATD with zero outside visibility. In solid weather, all of a pilot’s attention is on the instruments.

I’m a CFI-I and I’ve noticed that my instrument students also maintain better parameters in the zero-zero world of the AATD compared to flight with a view limiting device. Secondly, I find that the outside peripheral vision available with a view-limiting device is often a negative. It can be a distraction that degrades the instrument crosscheck somewhat similar to flying under a cloud deck with ragged bottoms.

When I practice in VFR conditions, if my safety pilot hasn’t located a target that’s inside of two miles, I’m giving up my instrument scan to add two more eyeballs to the target search.

Maybe the biggest downside with most view-limiting devices is that they not only limit your view outside the cockpit but inside the cockpit as well. Monitoring instruments cross-cockpit requires a noticeably larger head movement versus a sideways glance of the eyes.

On balance, I find the amount of “good” information that leaks into a pilot’s peripheral vision is more than negated by the drawbacks inherent with view-limiting devices. Maintaining a good instrument crosscheck with a view-limiting device may actually be more difficult than flying in the clouds. That’s probably a good thing.

Rocky Capozzi – Via email

Thanks, Rocky. In part because of that article, we recently upgraded our view-limiting device to a more traditional hood. The simulated instrument time that ensued, with a seasoned double-I along, was the hardest we’ve worked in a long time, in part because we couldn’t cheat and use our peripheral vision to help determine the airplane’s attitude. What we might call “peripheral cues” can help or hinder.


I just read your July 2021 article, “Personal Minimums?” again on I meant to write when I first read it in July; better late than never.

Finally, an article that expresses my uneasiness with the way personal minimums are usually taught. Thank you for putting it together; it gives me something to point to next time someone is preaching personal minimums.

Below are just a few examples of my own flying that would have busted any commonly taught personal minimum rules.

— Departing with 100-foot ceiling and ¼-mile visibility? Yes, I departed: The morning fog layer ended at 400 feet agl, the take-off alternate 10 miles away was already reporting VFR and delaying further would have given the next cold front time to roll over my destination.

— Launching in the center of a low-pressure system with steady (green-to-yellow Nexrad echoes) rain 200 miles in every direction and 400-foot ceilings at all airports? Yes, I launched on that training flight, but only after verifying that there is no convection or ice in the clouds and with a two-pilot crew, full tanks and a CAPS parachute. It was the best training flight I ever did.

Stefan Ballmer – Via email

Thanks, Stefan. We’ve also found that getting out into actual weather once in a while helps prepare us for the real thing. Of course, it ultimately is the real thing!


I enjoyed Tom Turner’s article in the January 2021 issue, “Non-Precision Stability.” I realize it is a year old but there are a few things I wanted to point out and ask. My experience is also that my instrument ticket is “of a certain age,” hence I grew up with the “dive and drive” (D&D) procedure, did it in the military flying fighters for 20-plus years and I now have spent another 20 years at a major international carrier.

That major international carrier doesn’t fly the D&D anymore, unless we are doing charters in obscure countries in Africa or the Middle East, and even then only with a whole bunch of briefing before reaching top of descent. Almost 100 percent of our approaches are an IAP with vertical guidance derived from the FMS/GPS/ILS.

I see you didn’t address the end game of the approach and I understand the gist of the article was about the constant descent angle and the D&D. But part of what happens with D&D depends on what happens at the MDA, not the MAP. The FAA’s FAR 91.175 states that we may indeed leave the DA, DH or MDA as long as we have the approach lights in sight. It says we may not go below 100 feet above the touchdown zone elevation (TZE) unless we see the rest of the ALS or other listed components, but we can leave the MDA. In my world, the callout at minimums is “Continue.” Then when I see at least one of the listed components, I call “Landing” and we land or “Go-around” at 100 feet above TZE. Fun-fun!

I have flown to places around the world (LFPG, Charles DeGaulle Rwy 09R) where at night it is a total black hole approach (Read: Very dangerous). The D&D here in shaky viz but able to see the ALS could drive someone to start down before reaching the VDP or other planned descent point calculated for the approach, and that could lead to a very dangerous situation. The dangers of leaving the MDA early and before your VDP are numerous and sadly framed in the blood of our fellow aviators. Why do we do it? Fatigue, get homeitis, etc. We have all been there, but I hope we are professional enough to ourselves not to go early.

Now, should most IFR pilots leave the MDA with just the ALS in sight? Probably not. I do it in a big Boeing with a HUD and EFVS. I have done it in real life (not just in the sim) and I am here to tell you it can be scary and gets your attention. If autoland isn’t an option and you have to click off the A/P close to the ground, it doesn’t give a lot of time if the winds are unfavorable. It’s a handful! Risk mitigation, thorough review and briefings are what makes them successful in the Part 121 world.

Many operators actually can use lower-than-published minima with appropriate FAA authorization. For a published 1800 RVR minimum, we can start the approach with 1200 RVR. And if we see the ALS in the EFVS or naked eye, we can go on down to 100 feet. My FOs can descend to 100 feet as well, if they see the ALS with the naked eye—no HUD on that side. 

I guess I feel strongly both ways. I understand the D&D and I understand the risk. There are so few places to do the D&D anymore—what with GPS and such—that it may well fade away at most airports in the USA. But if you have no GPS and are flying steam-gauge airplanes; stay sharp. It’s still a great discussion you brought up. In my Saratoga, my personal minimums aren’t such that I would be flirting with descending below MDA on the ALS only. In an emergency, could I do it? I hope so, but at my age, I hope I never have to press-to-test that button in my GA airplane! An ILS or LPV is my friend! I often reminisce about the D&D days! Flying was fun in the 1980s!

Great article and a great review, thank you!

John Denezza – Via email

Thanks, John!


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