Troublesome Definitions

Hi Readers: In my aviation experience I've found that certain definitions (FAA regulations, for instance) - acronyms and phrases - indicate a definite meaning, but relate to several separate operations. Here is a beginning list, covering a few basics, and items relating pretty much to complete flight. There are other definitions that will be covered, periodically, in future blogs. In fact, most of them are covered in the Pilot/Controller Glossary of the Aeronautical Information Manual (AIM).
Basics:
Ceiling - Height of the lowest layer of clouds or obscuration phenomena that is reported as
broken, overcast, or as obscuration.
Visibility - In units of distance to see and identify prominent unlighted object by day and
lighted objects at night, in statute miles.
Track - The actual flight path of the aircraft over the surface of the earth.
Tailwind - Any wind greater than 90 degrees to the longitudinal axis (magnetic) of the
runway.
Crosswind Component - The wind component measured in knots at 90 degrees to the
longitudinal axis of the runway.
True Airspeed - Calibrated airspeed corrected for altitude and temperature. True airspeed
increases with altitude.
Cardinal Altitudes - Odd or even thousand-foot altitudes or flight levels.
Weather:
Significant Weather - SIGMETS - severe and extreme turbulence, severe icing, widespread
dust or sandstorm that will reduce visibility to less than 3 miles.
Marginal Weather - Less than VFR conditions.
Hazardous Weather - Summary of SIGMETS and PIREPS such as thunderstorms, low
ceilings and visibilities not included in Hazardous Advisories.
Climb and VFR Flight:
Cleared As Filed - Aircraft is cleared to proceed IAW the route of flight filed in a flight
plan - does not include the altitude, DP, or DP transition.
Climbout - That portion of flight between takeoff and the initial cruising altitude.
Climb To VFR - ATC authorization for an aircraft to climb to VFR conditions, within certain
class surface areas when the only weather limitation is restricted visibility
- must remain clear of clouds.
VFR Not Recommended - An advisory by a FSS to a pilot during preflight or an inflight
weather briefing - when current and forecast conditions are at
or below VFR minimums.
Visual Meteorological Conditions - Weather conditions in terms of visibility, distance from
clouds, and ceiling equal to or better than minimums.
Special VFR Conditions - Conditions that are less than for basic VFR - permitted flight
under VFR class surface areas.
Approach and Landing:
Visual Approach - On an IFR flight plan, which authorizes the pilot to proceed visually -
ceiling 1,000' and visibility 3 miles.
Contact Approach - By visual reference, on an IFR flight plan, only by request from the
pilot, and when the ground visibility is at least 1 mile.
Straight-In Approach - Can be either VFR or IFR - visually and clear of clouds.
Runway Threshold - Relates to runway markings for visual, precision, and nonprecision
approaches, including a displaced threshold.
Touchdown Zone - The first 3,000' of runway beginning at the threshold.
Terminal Area - A general term used to describe airspace in which Approach Control
provides service to airport traffic.
Thanks for listening. R.S.

What Is Marginal Weather?

Hi Readers: Marginal weather is a subject which has bugged pilots for years, and has been the cause of many aircraft accidents - many fatal. Airline pilots, if given marginal weather conditions, automatically expect IFR conditions to follow, and of course they file IFR flight plans anyway. To the GA pilot, marginal weather, depending on the pilot's ratings, experience, and proficiency, is a matter to be dealt with on an individual basis. Too often the GA pilot fools himself by deciding the weather, deteriorating, will get better ahead.
Unless we have divine powers or a degree in meteorology or Aerology, we should not attempt to outguess the weather. Let's let the weather man - briefer, forecaster, or whatever name he goes by, handle the weather for us, X-C or local flight. We should listen closely to his words and ask the routine and difficult questions. As pilots, however, that still does not absolve us of not knowing what VFR, marginal weather, and IFR are and their differences. And the flight, local or X-C, is ours to plan and execute safely.
So marginal weather conditions are somewhere between VFR and IFR - let's get specific.
The FAA defines the term as ceiling 1,000' to 3,000' (AGL), and visibility 3 to 5 miles - interpreted as flight visibility (How expert are we in estimating visibility?). So marginal weather is just beyond VFR and that's usually where the problems start. Unless we are IFR qualified, we should immediately question our ability to continue with our flight plan (if we have one) or alter our course and revise our flight plan. Let's ask ourselves, do we honestly believe, knowing our capabilities, that we should continue the flight.
The National Weather Service, and other weather facilities, stand ready to assist us in our preflight preparations and flight planning, but do not define marginal weather or make decisions with respect to marginal weather. There can be a briefing for the flight, a forecast for the route of flight, or weather advisories. Readily available is METAR, FA (Area forecasts which give MVFR (Marginal VFR) reports for areas of 3,000 Sq miles at any one time, SIGMETS (4 hour period), and AIRMETS (6 hour period). TIBS ( area and route briefings) can be used, but is not considered a substitute for briefings by a weather Specialist (Call 1-800-WX BRIEF). Then there is also AWOS (Automatic Weather Observing System) at most airports, transmitted on a discrete VHF radio frequency - these airports listed in the FAA Airport Facility Directory.
There is a fine line between VFR, MVFR, and IFR conditions due to weather phenomenon such as low-level, layered clouds (associated or not associated with weather fronts) changing ceilings and visibilities with the advent of fog, dust, or haze conditions, even to the point of sky obscuration.
Most aircraft accidents relating to low ceilings and visibilities (flying into marginal weather) are the result of somewhat inactive pilots who are not qualified for IFR flight and, more often than not, attempt flight by visual reference into deteriorating weather conditions. Losing the visual horizon, they are immediately at risk to experience vertigo. If flying by reference to instruments is not accomplished immediately, control of the aircraft may be lost. Continued flight into adverse weather (marginal conditions) is the single cause of the greatest number of fatal accidents.
The best advice is to be aware of, and on the alert for, weather phenomena that may produce marginal VFR and IFR conditions. Above all, pilots should be honest with respect to their capabilities. Can I handle this weather? If not, do a 180 degree turn or change course or altitude immediately - don't wait. Get back to VFR conditions. There will always be another time - perhaps additional proficiency time.
Thanks for listening. R.S.

2007 December Accidents/ incidents - Part II

Hi Readers: Continuing from Part I, there were 9 other fatal accidents and 4 nonfatal accidents (1 serious injury) in the December 2007 accounting. The first accident, a Beech A36 -3 fatal - appeared as a typical VFR, no flight plan, 391 nm X-C flight encountering IFR conditions, colliding with mountainous terrain at 7,000 feet near Minersville, Utah. The reported weather at Melford, Utah (5,039' msl) was visibility 13/4 miles in light snow, scattered clouds at 2,500', overcast at 3,000', temperature -6 degrees C., dewpoint -7 degrees C. A private pilot occupied the left seat, an ATP was in the right seat, and a student pilot occupied the rear passenger seat. There were no known details regarding a weather briefing or weather check prior to takeoff or in flight.
The next 3-fatal accident involved a Beech V35B aircraft on an instrument flight plan in IFR conditions, and on an ILS approach to Springfield, Illinois. The pilot reported a problem (unk), but continued the approach. The aircraft impacted terrain 3 miles out from the Outer Marker, on the localizer centerline. The weather at Springfield was reported as visibility 2.5 miles with mist, overcast at 500' agl, temperature 3 degrees C., and dewpoint 2 degrees C. The next fatal accident, (2 fatal) involved a Beech 200 aircraft, a corporate - Executive flight, impacting a hangar at Salmon, Idaho, after takeoff in a snowstorm, trying to maintain VFR flight prior to clearance delivery of an IFR clearance by ARTCC. The weather conditions were not reported (obviously IFR conditions).
Another 2-fatal accident involving an instrument-rated pilot in a Cessna 210N on a X-C IFR flight plan collided with ground at Bloomsfield, Kentucky. The last known communication with ATC indicated that the pilot "read back" a clearance to descend from 8,000' to 6,000'. Radio and radar contact with the flight was lost. The weather was not reported. The next 2-fatal accident involved a Cessna R182 Commercial Flight Instructor and a student on a night, no flight plan, instructional flight from Orlando, Florida to Meridianville, Alabama. No weather was reported. The aircraft crashed near Woodland, Alabama.
There were two 1-fatal accidents involving collision with ground while maneuvering in night VFR conditions; one a Piper PA-28 near Ortiz, Washington, circumstances unknown, and a PA-32 on a night marginal VFR X-C flight near Warren, Wiisconsin. The weather near the accident site was visibility 6 miles, haze, overcast at 1,800 ', temperarture 2 degrees C. and dewpoint -2 degrees C. A witness near the accident site reported ground fog. Another 1-fatal Piper PA-28 involved a night forced landing when the engine quit near Augusta, Georgia; and a 1-fatal Beech 60 aircraft impacted terrain on a VFR X-C takeoff at Newcastle, Delaware. The weather was reported as wind 21 knots, gusting to 26 knots, visibility 10 miles, temperature 0 degrees C., and dewpoint -3 degrees C. At the accident site the gear was found retracted, the right flap was fully extended, and the left flap was fully retracted. Both flaps were observed extended prior to takeoff.
There were 4 Homebuilt aircraft accidents and 1 Sports aircraft accident, and 1 gyrocopter accident reported. One Homebuilt accident, killing the pilot, impacted trees on takeoff when the canopy opened and a fabric cover exited the cockpit and contacted the propellors. Two other serious injury accidents; one stalled on takeoff, and the other lost engine power inflight. Another Homebuilt, a Vans GA, lost complete power in flight and nosed over on landing. The pilot visually verified that both fuel tanks were full prior to departure (providing a range of 3 hours and 45 minutes of flight). At the accident site, both fuel tanks were found to be empty. The 2-fatal gyrocopter accident, an Althouse RAF 2000 GTX, contacted ground near Cromley, Texas, apparently an engine problem. A Sport pilot in a Garniss STOL 701 was killed during an apparent buzzing accident.
Four other accidents were reported, one a Mooney M20C when the engine caught fire inflight at night. The pilot managed a forced landing near Phillipsburg, Kansas. The pilot and a passenger received serious injury. Two ATp's in a Cessna 551, with 6 passengers, landed at Coeur d' Alene, Idaho in 21/2 inches of snow slush, and departed the runway when the nosegear failed. The pilot was told there was 3/4 inch of snow on the runway. Another, a Piper PA-30, sustained substantial damage when the landing gear collapsed during the landing roll at Bridger, Montana. And a Cessna 152 was damaged during a forced landing following loss of engine power during cruise near Ft. Worth, Texas. The student pilot was not injured.
The majority of the fatal accidents were weather-related. We'll wait out the NTSB Investigator's findings on those accidents.
A word or two regarding the GA and fatal accident rates for 2007. Some of the aviation experts have stated or indicated a reduction in those rates for 2007 from 2006. The data, however, based on the best available, does not really indicate a reduction. Rather, a slight increase in the GA rate and a slight decrease in the fatal accident rate. Based on accidents / 100,000 flying hours, the reported rate for 2006 was 6.64 and 1.32. The computed rates for 2007, based on NTSB accidents through November 2007 and the addition of the December accidents result in rates of 6.78 and 1.24 respectively. And a higher number of
accident and fatal accidents in December would increase the rates, and a lesser number of flying hours (from the estimated) would also increase the rates.
Thanks for listening. R.S.

Aircraft Icing

Hi Readers: Now that we are in the winter weather of the year, we must all face the fact that, for flying, icing conditions on the ground or in the air is upon us (although icing conditions can occur in flight at any time of the year depending on the weather systems). Icing conditions on the ground before flight without de-icing is dangerous (and foolhardy) and icing conditions at altitude without de-icing and anti-icing are dangerous and lethal. In flight, icing can cause rapid loss of altitude and/or loss of control in minutes. If your airplane is not equipped with de-icing and anti-icing gear, or not certified for flight in icing conditions, its your knowledge and good judgment of the weather against nature.

Although I won't dwell on the many aircraft accidents over the years caused by icing, some of the worst fatal accidents have been caused by icing - principally due to our lack of knowledge, our judgment, and lack of anti-icing equipment. General Aviation (GA) and Commuter type (Part 23) airplanes are the most vulnerable since they are flown at the lower altitudes where icing conditions occur, and most of the airplanes are not equipped with ice-prevention gear or the intention of flight was not to encounter weather conditions.

How, then, does inflight icing occur? Well, we have to be flying in, around, or through stratus and cumulonimbus clouds containing water droplets at or nearing freezing temperatures, and nature takes care of the rest. There can be induction icing - ice forming around the engine air intake (particularly bad for jet engines since ice will form in chunks which may be ingested) or structural icing, either as clear or rime ice, formed when supercooled water droplets impact the wing and control surfaces (top and bottom) freezing in a solid sheet of ice or in a irregular shape - usually between zero degrees and minus 10 degrees centigrade. Such icing has been encountered in a cumulonimbus cloud at temperatures down to minus 25 degrees centigrade. Mixed icing, clear and rime ice, which result in an irregular shape on airfoils, can occur while flying through snow, ice pellets, or small hail.

The effects of ice on the airplane are cumulative - thrust is reduced, drag increases, lift lessens, and weight increases. The combined results are an increase in stall speed and a deterioration of airplane performance. In extreme cases, 2" to 3" of ice can form on the leading edge of an airfoil in less than 5 minutes.

A recent Cessna 208 Caravan accident near Mt. Ranier, Washington, reminds us that icing problems are still with us, in spite of de-icing and anti-icing equipment, along with GPS and digital instruments. The NTSB and Cessna Aircraft are still investigating.

In Airline and Part 121 flying (all IFR flight plans), cancellations and delays due to icing conditions can cost millions of dollars in one day. The cost of de-icing fluid, at a cost of 3 to 4 dollars/gallon adds to their problems. Part 121 operations covers the transport aircraft icing conditions. Part 135 and 91 flying is covered under 135.227 and 91.527.

NASA, FAA, and NTSB have been conducting research on aircraft icing problems over the years (see applicable icing FAA Advisory Circulars) and as of 6-1-07 the FAA was still working on a proposed rulemaking (Docket #FAA-2007-27654), titled Activation of Ice Protection, applying, principally, to Part 25 Transport Category airplanes. (It is hoped that FAA will follow with Part 23 aircraft). Under the proposal, Aircraft Manufacturers would be required to add an ice-detection and activation system to the present de-ice and anti-ice systems, and mandate that the protection system operate automatically and continuously. I think there is going to be a lot of discussion on this proposal.

How to avoid flying in icing conditions? For GA and Commuter aircraft, use all available weather services and reports to pinpoint icing areas and then plan on avoiding them. If you encounter icing conditions at altitude, use your available de-icing and anti-icing equipment immediately, change altitude up or down, and/or make a change in course (not necessarily 180 degrees since the true direction of the weather system is not known). Leave the autopilot off. Replan your flight or land at the nearest available airport (that will accommodate your airplane) and wait it out.

Proper preflight action includes, on filing an IFR flight plan, determining the freezing level and the levels above and below for weather precipitation areas. If your flight route penetrates the freezing level, request a new altitude or route. Make use of appropriate SIGMETS, AIRMETS, and PIREPS, and any other source of inflight weather advisory in planning and executing en route flight. In general, make a habit of checking FAA Advisory Circulars - FAAs method of advising new developments or action on pertinent problems.

Thanks for listening and Happy Thanksgiving! R.S.

Ceiling and Visibility

Ceiling and visibility are two basic weather elements which must be considered in all flying beginning with your flight planning. Normally we don't give the two elements much thought. We look at the sky - it's either cllear or cloudy. And we look out and around to see how far we can see objects. But for flying, the broad perspective must be narrowed to specific judgments.
The FAA's definition of ceiling is "the height above the earth's surface of the lowest layer of clouds or obscuring phenomena that is reported as broken, overcast, obscuration, and not classified as thin or partial". Pretty wordy and a little confusing, yes?
Well, let's get practical - if you cannot see clouds in the sky or you have something like fog or haze, you have either no ceiling at all or you have ceiling zero, depending on whether the condition is thin or heavy in obscuration.
Weather Observers classify clouds 3/10 or less as scattered, 6/10 as cloudy or a ceiling, 10/10 as overcast. And, of course, heavy fog would be obscuration or ceiling zero.
Now visibility is another matter. We usually think of seeing objects in terms of miles (statute), say 1/4 mile, 1/2 mile, 1/ mile, 3 miles, etc., a matter of distance judgment - relating much to visual acuity used in connection with takeoff, landing, and clearances, and VFR and IFR flight. In fact, ceiling and visibility appears as the first pair of elements used in our flight planning.
As stated (all too simply) in the FARs (Federal Air Regulations), IFR flight is weather conditions below the minimums for flight under VFR conditions.
In any case, to the pilot ceiling means dealing with clouds, sky cover, at what altitudes, and their movement over time. Visibility relates to all kinds of weather conditions - rain, snow, fog, smoke, and haze in connection with all phases of flight and appears perhaps as the first defining factor in planning whether you fly VFR or IFR.