April 1, 1999
MARC E. COOK
Rejoice, Californians, spring has sprung and the pesky jet stream has begun its migration northward — which means that summer is just around the corner. With the warmer weather and the predictable Pacific highs that hang around for a good chunk of the year comes haze. Low visibility, even when the tower or flight service is calling it VFR, can be more than just a distraction.
From the eastern deserts to the Los Angeles Basin to the Silicon Valley, low visibility means greater work load for the pilot and a heightened concern about seeing other VFR traffic. Let's face it, there are times when the en route visibility is just three miles. Yes, it's legal VFR, but depending upon the position of the sun, you may be in for a real adventure just seeing where you're going.
Yet this sky-obscured season doesn't have to see you waiting on the ground. Here are some suggestions for coping with the low-viz blues:
Know the rules. With few exceptions, the visibility limitation you need to keep in mind is 3 statute miles. In controlled airspace below 10,000 feet during the daytime, 3 statute miles is the minimum legal VFR flight visibility. Keep in mind that's flight visibility; however, in Class D airspace, it's the reported visibility that's controlling. Above 10,000 feet in Class D airspace and at night, the minimums increase to 5 statute miles. An important exception is the provision in FAR 91.155 for legal VFR flight in uncontrolled (Class G) airspace with just 1 statute mile visibility.
Special VFR — use it. What do you do if your home base, a towered airport, is reporting sky obscured and 2 miles' visibility? Request a special VFR clearance. Remember, though, that you must receive a clearance to depart, transition, or land under special VFR. To be legal for special VFR at night, both you and the airplane must be qualified to fly IFR. If you're not IFR-current or the airplane isn't legal for IFR, you can't fly the special at night. Under SVFR you can fly with as little as 1 statute mile visibility as long as you remain clear of clouds.
For some reason, a lot of pilots are hesitant to use a special VFR clearance. Perhaps many pilots forget it is available; ATC will not offer a special VFR, you have to ask for it. It's a tremendous tool under the right circumstances. You shouldn't use it in deteriorating weather, for example, because neither the tower nor the local ATC is expecting you to ask for a right-now IFR clearance. Nor does SVFR give you the flexibility of an IFR-to-VFR-on-top clearance, particularly in penetrating cloud layers. But if it's a case of the morning smaze taking its time burning off, the special can be a real treat, putting you out ahead of all those guys in the runup area waiting for a pur sang IFR clearance.
Clean the windshield. How many times have you launched, only to discover that you meant to get the last month's worth of bug residue off the windows but forgot? Do it regularly in the summer months. Window manufacturers recommend using plain water and a bare hand (leave your rings at home) to remove the first layer of debris. If you need to detach particularly stubborn bugs, add a bit of mild dish soap to the water and, again, apply by hand. Rinse thoroughly and wipe with a clean, soft cloth. Then you can use any of the common acrylic cleaners to get the water spots if you wish. Some of these cleaners contain mild waxes, making them good for preventing further contamination and for filling in small scratches. While you're at it, get the inside of the windows, too. Plastics common in aircraft tend to out-gas chemicals when they're hot and contribute to a film of gunk on the inside. Never use a dry towel against a dirty windshield.
Buy good polarizing sunglasses. Many pilots feel that quality sunglasses help them to see through the muck. It's true that eyewear with polarizing filters can help to minimize the glare created by light reflecting off the airborne particulates. But beware: Some glasses have very strong filters, which can make some cockpit displays hard to read.
Navigation is your friend. It'll be harder to see important landmarks, so be sure to keep up with your navigation. This is particularly important if you're unfamiliar with the area. Use whatever you have on board, but let it be said that there are few better utilities than a moving map display hooked to a GPS. With this tool, it's quite a simple matter to keep yourself out of special-use airspace. Take the time to use the GPS properly, too; map out your VFR course and plug it into the flight planner. You shouldn't have to be entering the next waypoint at the same time that you're trying to make out metal in the murk.
Finding the pavement. This may be more of a Southern California phenomenon — you're coming home from a weekend trip, right at sunset. The airport is using the runway facing more or less west. You've managed to find the field in the haze; but now, as you turn final, you see — nothing. From your perch at 500 feet agl, the windshield is pure California brown.
If this is your home base, you'll probably revert to familiar landmarks and muddle your way to the threshold. It may be five miles in haze to the tower, but it's much less in flight, so be prepared.
Avoiding this predicament is relatively easy. One option is to overfly the field and enter a very tight, steep approach to the runway. Usually, flight visibility will be good directly down or at a sharp angle to the runway, while visibility on the normal glideslope is miserable. It'll be good spot-landing practice for you, too. Another option is to fly the localizer or ILS to a landing. There's no reason that you can't do this under VFR as long as you advise the tower of your intentions.
In a similar vein, you can program your moving-map GPS to guide you down the final for the runway in use. Remember that the database in your GPS will direct you to the airport reference point, which may or may not be anywhere near the runway that you're using. You can program the end of the runway into memory by creating a user waypoint; even doing this bit of latitude/longitude gobbling in the runup area will suffice. Next time you're flying down final in good visibility, make another user waypoint on the extended centerline of the runway, say three or five miles out. This is not a do-it-yourself instrument approach, it is merely an aid in VFR weather.
Be seen. Display your strobes and landing light in hazy conditions to give the other guy a chance to see you and to help avoid a close encounter.
Safety and Education,
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