PIREPS

Hello Readers: Before we get to PIREPS, have you thought about your weight lately? Do you know what your Body Mass Index is? BMI will give you a good indication of where you stand on weight. This through the courtesy of Karen Miller-Kovach, RD, Chief Scientific Officer of Weight Watchers In'l, the formula: Divide your weight, multiplied by 703, by your height in inches squared. You should comeout somewhere between 20 and 30. 20 to 30 - optimal, 25 to 30 - overweight, and 30+ - Obese.
Now the PIREPS - What are they? Get out your Acronym reader.
Pilot reports are inflight, usually en route, weather reports to help other inflight pilots know what is up ahead of them. You can check PIREPS either prior to your takeoff or en route. Or if need be, you can contact the pilot directly to ask his assesment of the weather. Normally you would contact your FSS (Flight Service Station) and get EFAS (En route Flight Advisory Service).
EFAS (Flight Watch) is a service specifically designed to provide, upon pilot request, timely weather information pertinent to type of flight, intended route of flight, and altitude. This service is within the FSS system, and is listed in any Airport/Facility Directory.
FAA, through the air traffic facilities, is required to solicit PIREPS when the following conditions exist - reported or forecast:
1. Ceilings at or below 5,000 ft.
2. Visibility at or below 5 miles - surface or aloft.
3. Thunderstorms and related phenomena.
4. Icing conditions of a light or greater degree.
5. Turbulence of a moderate degree or greater.
6. Wind shear, reported or forecast, and volcanic ash clouds.
Pilots are urged to cooperate and volunteer reports of cloud bases, tops and layers; flight visibility; precipitation; visibilitity restrictions such as haze, smoke, or dust; wind at altitude; and temperature aloft.
PIREPS should be given to EFAS, AFSS/FSS, ARTC (Air Route Traffic Control), and terminal ATC. The EFAS (Flight Watch) facilities, as mentioned, has the specific duty of collecting and exchanging PIREPS with en route aircraft. If pilot are not able to make PIREPS by radio, then the reports should be given to the local FSS upon landing.
Some of the uses of PIREPS areas follows:
ATCT (Tower) uses the reports to expedite the flow of air traffic locally.
AFSS/FSS uses the reports to brief other pilots inflight and en route.
ARTC uses the reports to expedite the flow of en route traffic.
NWS (National Weather Service) uses PIREPS to verify or amend conditions contained in Aviation Forecasts and Advisories, and pilot weather briefings.
There are numerous pages of information in the FARs regarding PIREPS, their importance, and specifically how to prepare and use them. Pilots should take the time to digest this information in the FARs, with the idea of participating in PIREPS. Thanks for listening. R.S.

Aviation News, Interest, and Careers

Today we have a 3-way message of people making news, promoting interest in aviation, and spreading the word of careers and jobs in the aviation field.
First of all we'll say goodbye to FAA Administrator Marion Blakely - she is to vacate the Administrator post 9-13-07. Enough said. Now, Mr. Bush, let's fill the position with loads of aviation experience and dedication towards solving the current problems in FAA, in all types of flying, and plan for a healthy expansion of aviation demands.
Secondly, I'd like to congratulate young Barrington Irving (23) who flew around the world - solo yet - in a donated Columbia 400 airplane, becoming the youngest person to accomplish such a feat (I learned this from AVWEB's Podcast of 8-24-07). I'm sure it took guts and determination. As reported, Irving is now focusing his efforts on Experience Aviation - an aviation group he founded in 2005 to get people interested in aviation. This is the spark aviation needs and I'm sure we'd like to hear more about him and his group.
I would also like to point out and give credit to AOPA (Aircraft Owner Pilot Association) and it's energetic President Phil Boyer - champion of the rights of GA pilots for the past 15 years - for the dedication to and continued aviation oversite. There are other associations (NBAA, ATA, etc.) that are monitoring our aviation interests, also.
Although AOPA doesn't need me to trumpet their programs (I've been a member for years), I'd like to point out their support of the young people and their desire for careers and jobs in the aviation field. AOPA cites 60+ careers and jobs needed in aviation - not just pilots, all a part of an industry of 1.3 million jobs and $158 billion in annual economic activity.
Some of the career openings cited are Airline and Other Career Pilots, Airline and Airport Operations, Aircraft Manufacturing and Maintenance, Scientific and Technical Services (engineers, architects, cartographers, meteorologists, etc.), Food Service, Law Enforcement, Avionics, and others. I will add Government Service careers such as Air Traffic Controllers in the FAA and Air Safety Investigators in the NTSB.
AOPA has a world of information for the asking - however, you need to become a member ($39/yr.). Your key to membership and a start is a strong interest in aviation and the willingness to learn and work. A good contact is the Pilot Information Center - 1-800-872-2672 or www.aopa.org on your computer. If I can help you get what you need, let me know. Thanks for listening. R.S.

Near - Miss Incident of Jets at LAX

Now that everybody has heard about the near-miss incident of Westjet B-737 and Northwest Airlines Airbus A320 in daylight at Los Angeles airport on 8-16-07, let's take a quick look and see what did happen and why. NTSB is investigating and the factual report will be forthcoming as usual.
A runway incursion or a near-miss? Some, including NTSB are calling it a runway incursion. However, so far the facts reported show that an incursion did not occur. It was definitely an incident, one that could have been disastrous for all. As a pilot I shudder to think what could have happened, and I'm sure the pilots involved have already relived the incident several times since. The passengers - how lucky they were that a collision did not occur. From the nose of the Westjet B-737 to the wingtip of the Northwest Airbus there was all of 37 ft.
So let's sort out the facts (or the reported facts) at this point. The Airbus was cleared for takeoff on Runway 24 L. The Westjet B-737 had just landed on Runway 24R and was positioned on Taxiway Y, wanting to cross Runway 24 L. Reportedly, he was cleared by Ground Control to cross Runway 24L. The Airbus has started takeoff and reached about 155 knots, probably ready to rotate. The B-737 managed to remain clear - we don't know exactly where on Taxiway Y - reportedly crossing the hold short line but not entering Runway 24, either moving or stopped.
The Westjet B-737 had arived from Calgary, Canada carrying 136 passengers and the Northwest Airlines Airbus was taking off with 150 passengers. At this point it appears that the PIC of the Airbus was properly cleared for takeoff by the Tower Controller. ( I do wonder if the PIC observed the the Westjet movements, which would have been ahead of him.)
The PIC of the Westjet would have to been cleared by the Tower Controller to cross Runway 24L - he or the Ist Officer switched to Ground Control without authorization from the Tower Controller during exit on Taxiway Y. The Ground Controller apparently assumed that the Tower Controller had instructed the Westjet to cross Runway24L.
It appears that almost all of the blame lies with the Westjet Captain and the Ground and Tower Controllers. In takeoff and landing operations there is no room for assumptions. The coordination betwen Controllers in the Tower appears lacking and the misunderstanding between the Ground Controller and the Westjet, particularly on the part of the Ground Controller, was primary to the incident. I wonder too, if the ground airport radar in the Tower was functioning for a reference.
In most respects, the misunderstandings shown in the incident remain inexcusable - but they do happen. In fact, they are happening quite frequently over the continental U.S. We'll see what the NTSB Investigators have to say. Thanks for listening. R.S.

The Lost Is Found

Recently, while browsing through the small library where I live, I uncovered a story that I had been seeking for a long time. To wit: How was young Joe Kennedy (eldest son of Joseph and Rose Kennedy, and brother of Jack and Bobby and Ted Kennedy) lost during WWII?
Doris Kearn Goodwin's story - The Fitzgeralds And The Kennedys - an American Saga - published in Readers Digest Todays Best Nonfiction in 1987 told me what I wanted to know.
Joe was commissioned in the Army Air Forces as a B-24 pilot and had already accomplished 39 missions in the European theater and was due to come home in two weeks. But D-Day (Normandy) was coming up and Joe volunteered to stay another month to fly patrols in the PB4Y over the English Channel (Operation Cork). The operation was a success - not a single ship of the invasion fleet was lost to German U-boats.
After D-Day the Germans began propelling V-1 rockets into London from giant concrete bunkers on the French coast. Civilian casualties were high.
A plan was then conceived - PB4Y's would be gutted and loaded with explosives and flown to be targeted to the bunkers. Joe kennedy and copilot Wilford Willy volunteered for the dangerous mission - to fly the airplane across the channel toward the target, Calais, a giant concrete bunker, believed to be the launching site of the V-1 rockets.
The flight was scheduled for August 12 (D-day was June 4, 1944). At 5:52 Joe and Wilford lifted off from the channel in the PB4Y loaded with high explosives. At 6:10 pm, at an altitude of 2,000 ft, Joe engaged the autopilot and called the mother ship to take over. They were to then bailout. At 6:20 pm a huge explosion occurred. Joe and Wilford never made it, and were never found. Real heroes, by any count.
I thank Ms Goodwin and Readers Digest Books for my taking liberty with this account.
Thanks for listening. R.S.

The Relative Humidity - Dewpoint Relationship

Before we get started today - Did you know that our global warming of today is only 6 degrees C. higher than that of the Ice Age? But that increase in temperature may cause heat waves, intense precipitation, droughts, and tropical storms. The sea level will be rising, too, due to thermal expansion of the oceans and the melting of glaciers.

Okay - Relative humidity (RH) is the actual amount of moisture in the air, compared to the total amount of moisture the air could hold at the current temperature. Relative - yes. If the RH is 70%, the air is holding 70% of the total amount of moisture that it can at the current temperature and pressure. Normally we think about RH in terms of how it affects our body temperature - if the humidity is high we feel the heat or if the humidity is low we feel much better. In aviation we are more concerned with the Dewpoint (DP)/temperature relationship and how it affect the air in which we fly.
The relationship actually defines the concept of RH. Given in degrees, the DP is the temperature at which the air can hold no more moisture. Perhaps, in simpler terms, the air is saturated with moisture. When that temperature is reached the moisture begins to condense in the form of fog, dew, frost, clouds, rain, hail or snow. The relative gap has now closed and the RH is 100%. Since the amount of moisture the air can hold is driven by the temperature, we find that as the temperature increases the air can hold a greater amount of water.
If a cubic meter of air has 17 grams of water vapor at saturation, at a temperature of 68 degrees Fahrenheit (F.), the RH would be 100%. Any further cooling would result in condensation of the vapor. If we lower the temperature to, say, 49 degrees F., the air can only hold 9 grams of water vapor, which would be saturation, but the RH would still be 100%. If we raise that temperature to 86 degrees F., the 17 grams of water vapor will be 56% of the 30 grams of water that can be held, so the RH is 56%.
The spread between the current temperature and the DP can be useful in determining, say, a cloud base. If your current temperature was 85 Degrees F. and the forecasted DP was 71 degrees F., taking the spread of 14 degrees F. and dividing by a convergence (saturation) rate of 4.4 degrees F. and dividing by 1,000, you will have determined an approximate cloud base of 3,180 ft above ground level.
How does the air reach its saturation point? When warm air moves over a cold surface, the temperature of the air drops and reaches the saturation point. The saturation point may also be reached when cold air and warm air mix, or when at night the air cools on contact with the ground. Obviously, at lower temperatures the DP spread or saturation point is less because the amount of water vapor the air can hold is less at that temperature.
A remaining point to think about, then, with respect to flight, is that DP takes on an added importance at lower temperatures since the spread is less and what that spread indicates - freezing, icing, snow, etc. These indications will be even more important at altitude.
In order for clouds to form there must be adequate water vapor and condensation nuclei, as well as a method of cooling. When the air then cools and reaches its saturation point, the invisible water vapor changes to a visible state by latching on to the miniscule particles of matter or nuclei.
Usually, the temperature - DP relationship is given in weather broadcasts and other reporting systems rather than RH, since the relationship is more meaningful and a better indicator of weather aspects. The temperatures are almost always reported in degrees Celcius.
The various types of weather reports and reporting systems will taken up in future blogs.
Thanks for listening. RS.

The Relative Humidity - Dewpoint Relationship

The Air You Fly In

The air you fly in can be stable (no vertical movement) or unstable (vertical air movement resulting in turbulence and convective activity). Most of the time you will find the latter. You are more likely to find the stable air at night and after the sun sets. Unstable air can lead to significant turbulence, extensive vertical clouds and severe weather such as a thunderstorms and tornadoes with associated icing and hail. The sudden vertical movement of your airplane will be your warning to change course, altitude, and perhaps destination.
What causes these vertical movements? Rising air expands and cools due to the decrease in air pressure as the altitude increases. The opposite is true of descending air - as the pressure increases, the temperature of the descending air increases as it it compressed. This is called adiabatic heating or adiabatic cooling - the rate at which temperature decreases with an increase in altitude - referred to as the lapse rate. Normally this rate will be 3.5 degrees Fahrenheit (F.) per 1.000 ft.
Why does the air ascend? I guess the simplest explanation is that water vapor in the air (lighter than air) decreases the air density causing it to rise, and conversely, as the water vapor becomes less, the air becomes more dense and tends to sink. Since moist air cools at a slower rate as it rises, it it less stable than dry air. This is reflected in a dry adiabatic lapse rate (5.4 degrees F./1,000 ft). The moist adiabatic lapse rate vareies from 2.0 degrees F. to 5.0 degrees F./1,000 ft.
To sum it up, the combination of moisture and temperature determines the stability of the air and the resulting weather. Cool, dry air, then, is very stable, leading to generally clear weather. The greatest instability occurs when the air is moist and warm, such as in the Tropics in the summer. There, thunderstorms can appear on a daily basis.
But wait, there's more. There are times, quite often I might say, that an inversion of temperature occurs - the temperature of the air increasing instead of decreasing - usually a shallow layer of air at lower altitudes. The top of the layer, keeping the weather and pollutants trapped below. If the relative humidity of the air is high, clouds, fog, haze or smoke may appear, resulting in lower visibility.
Back to thunderstorms - they can be sudden and dangerous. I became well acquainted with thunderstorms and unstable air in WWII. I remember a night flight I made in a C-47 from Dunnellon, Florida to New Orleans, Louisiana. Even at night I could see the outline of this tremendous storm near our destination, and we bounced around like a yoyo. I got in to New Orleans by sliding under the storm at 4,000 ft. It shook me up so much that I ordered oyster soup instead of oyster stew for dinner. There is a big difference - the second surprise that night. Later, in the South Pacific, I met unstable air and thunderstorms on a daily basis. And even later, over New Mexico in a T-33 at 43,000 ft, I looked up to a cumulo-nimbus cloud top of at least 60,000 ft.
You can't change how nature handles it's air, but you can study the weather relative to unstable air. Get a good weather report. And when you meet that gruesome-looking thunder cloud, say to yourself, "I can't fly through it, or under or over it, I'd better change course and altitude, or maybe my destination".
We'll take up relative humidity and the temperature/dewpoint relationship soon. Stay with me. RS.