Tuesday, February 16, 2010

Colgan Air Pilots poorly treated by NTSB summary statements

The following statements are just my opinions.
I feel the National Transportation Safety Board (NTSB) recent release of summary statements treat the pilots poorly.
Could a three man crew have influenced the outcome?

Sunday, February 14, 2010

Part 5 Integrity and Current World GPS status

The integrity of any radio signal a pilot uses may be more important than the accuracy of the signal.  As we operate in a "safety of life" enviornment it is imperative we become aware as soon as possible when ever the signal becomes unreliable or is  lost.

Prior to augmented GPS signals being available, we relied upon the GPS receivers built in Receiver Autonomous and Integrity Monitoring (RAIM) and Fault Detection and Exclusion (FDE) to supply warnings.  These warning may take as long as 10 minutes before it is delivered to the pilot.  This is not acceptable for most of our operations.

Both Ground Based Augmentation Systems (GBAS) and Satellite Based Augmentation Systems (SBAS) are able to warn the pilot with almost no time delay. It should be clearly apparent to the pilot the superior advantage of having an augmented signal. As the WAAS capability does not add to the cost of the receiver, I am astonished how few corporate aircraft are equipped with it.

Many older airliners are still not equipped with GPS, let alone WAAS GPS as there is no regulatory requirement to do so. The superiority of the GPS signal to provide navigational information should insure that it is installed on all aircraft. The increased integrity of the augmented signal along with the increased accuracy also should insure it is installed on all aircraft.

I have been suggesting that all pilots carry their own personal battery powered portable GPS receiver to cover the possibility of encountering an event where the loss of the aircraft's GPS receiver happens. A GPS has the ability to deliver us aircraft ground speed. In the event of the loss of pitot and static instruments or loss of indicated airspeed information, you can apply and wind speed estimate and use the ground speed as a substitute for indicated air speed.

If the GPS receiver has at least 4 satellites in view, it will calculate our altitude giving us a chance to substitute for our altimeters.  The GPS will also calculate the aircraft track angle and update that information at least once per second.  This will permit us to use the GPS for turn information as well.

Have you ever viewed the GPS calculated altitude in your aircraft?  Does the Flight Management System (FMS) on your aircraft permit you to view the GPS calculated altitude?  Most FMS systems will allow you to view it on the sensors page but some older units do not allow it. Assure your self you have the ability to view it and you know how to access it.

Back in 1996, an Aero Peru Boeing 757 with 75 crew members and passengers took off at night in Instrument Meteorlogical Conditions (IMC) over water with duct tape covering the pitot and static ports. The crew suffered from unreliable incorrect instrument indication as well as numerous aural warnings and warning lights.  The resulting confusion of the flight crew ended 30 minutes later when the aircraft stalled and crashed into the water with all on board killed.

If the crew had available a portable GPS receiver , they would have had enough information to avoid stalling the aircraft and would be alive today. Do you carry a portable GPS receiver on board your aircraft today?

Part 4 WGS-84 What is it? Current World GPS Status.

Which is most  important where GPS navigation systems is concerned, accuracy or integrity? Well first of all, how accurate are the current GPS signals? The US Coast Guard says the current system has an accuracy of plus or minus 7 meters horizontally and plus or minus 12 meters vertically. Prior to Selective Availability being turned off on May 2, 2000 the accuracy of the signal was  plus or minus 100 meters horizontally and plus or minus 300 meters vertically.

The accuracy of the signals was much improved when the Wide Area Augmentation System became fully operational over North America in 2003.  When this happened, the accuracy became plus or minus one meter both horizontally and vertically and never worse than plus or minus 2 meters both horizontally and vertically.

The cost of WAAS capability is not significant today.  Even the most basic portable GPS units such as those used by joggers and physical fitness advocates  cost less than $100 and offer WAAS accuracy.

A Local Area Augmentation System (LAAS) is in development which delivers high accuracy signals to a local area.  Usually about 20 to 30 miles in radius, it has the advantage of only requiring one ground station which will provide precision curved path approaches to all runways at airports within its coverage area. The accuracy of the Local Area Augmentation System is plus or minus one meter both horizontally and vertically.

GPS is capable of delivering millimeter accuracies when differential techniques are used by surveyors.  These require a highly accurate reference point and a transmitter. Whether we require this level of accuracy when operating our aircraft has not been answered yet.

Saturday, February 13, 2010

Part 3 WGS-84 What is it? Current world GPS status

I used the word "interoperability" in my last post. This is an important concept as additional Global Navigation Satellite Systems (GNSS)  are built.  China is well on the way to having the third system in the form of Compass and the Europeans will  be fourth with their Galileo Global Navigation Satellite System.  A possibility exists that India may not be willing to rely on other countries providing critical navigation information and build their own system.

As all these systems come on line, increased benefits of better accuracies and integrity will result if all meet interoperability standards.  Both Ground Based and Satellite Based Satellite Augmentation Systems (SBAS and GBAS) enhance the GPS signals where both accuracy and integrity are concerned. North America, the USA, Canada and Mexico have joined together to create the Wide Area Augmentation System (WAAS).  It has been fully operational for more than 7 years. The European Union has declared their European Geostationary Navigational Overlay Service ( EGNOS) operational on October 1, 2009.

Much of the rest of the world have invested in either Ground Based Augmentation Systems (GBAS) or Satellite Based Augmentation Systems (SBAS) systems. These include India's GPS And Geostationary Augmentation Network (GAGAN), Japan's Multi-transport Satellite Augmentation System (MSAS) and Russia's System of Differential Correction and Monitoring (SDCM).  Interoperability between all the augmentation systems is a  goal well on the way to being met.

Thursday, February 11, 2010

Part 2 WGS-84 What is it? Current world GPS status

WGS-84 Part 2
Oblate Spheroid

In Part 1 of WGS-84, I stopped at the point where I wrote the Russian Global Navigation Satellite System (GLONASS) is referenced to the PZ-90 geodetic model.  The WGS-84 geodetic model as well as the PZ-90 geodetic model are really both descriptions of the shape of the earth.  The earth is not a perfect sphere but has ellipsoid characteristics. In order to attain the highest accuracies using the satellite navigation systems, the shape of the earth must be taken into account.  As a result of the development through the years of more and more accurate measurements being made, the geodetic models have achieved unheard of accuracies.
  Now, what is the difference in location accuracy between  the PZ-90 (Parametri Zemli 1990 (PZ-90, or in English translation, Parameters of the Earth 1990, PE-90) geodetic datum, standard and the WGS-84 standard? 
The difference between the coordinates of points on earth in WGS 84 and PZ-90 has been found to be less than 15 m (average: 5 m). As I said in my previous post, "not much". I know that you have been advised to not rely on your GPS receiver while flying in non-WGS 84 countries.  It is certainly not permitted to utilize your GPS for approaches.
The Russians have made a strong commitment to completing their Global Navigation Satellite System (GLONASS) with their most recent launch of 3 new modernized "M"satellites on December 14,  2009. They presently have plans to launch 5 additional satellites in 2010 completing the constellation of 24 satellites.  The system should achieve full operational capability near the end of this year.
The manufacturers of GPS receivers are aware of the need to supply receivers capable using both GPS and GLONASS signals as well as European Galileo signals.  The buzz word of "interoperability" is flowing through the GPS community presently. Novotel and Thales both make available receivers today capable of using both sets of signals.  

More to come in Part 3 of WGS-84 What is it?

If any of you who read this flies into Russia, I would appreciate your comments on your real world experience concerning your observations on the accuracy of your GPS guidance.  Are you able to notice any difference when looking out your window? Please feel free to comment on the blog.

Wednesday, February 10, 2010

Part 1 WGS-84 What is it? Current world GPS status

WGS-84 or World Geodetic Standard-84 is a specific standard by by which surveyors describe their work results and cartographers produce maps. Surveyors have worked to as many as 200 different standards which vary according to the time period in which they were established and which parts of the world use them and which of the surveying results are of prime importance. The many standards developed through the years are due to the continuing development of more and more accurate means to acquire data.  One of the more accurate ways to gather data today is the result of the establishment of the Global Navigation Satellite Systems (GNSS). Data acquired by the GPS can be as accurate as plus or minus a centimeter.

My old Garmin GPS-195 hand held battery powered GPS receiver has the capability to accept any of 110 different geodetic standards.

The Global Positioning System (GPS) delivers user services today based upon the WGS-84 model.  If a country has utilized other geodetic standards to locate its airports and runways, an error in what GPS is telling you and what you are looking at out the window will occur. This is not a very good situation if you happen to be using your GPS receiver to accomplish an instrument approach. The best source for you to use to determine if the country you are flying in is using the WGS-84 model for surveying its airports is found at the Jeppesen web site.  Jeppesen has a page that will deliver this information for you to consider.

The current Jeppesen WGS-84 page is dated March 2009.  If you want the most current data for a country, it will be necessary to access its Aeronautical Information Publication (AIP).  Many of the AIP's are available for free down load and viewing on the internet.  For example, click here for the AIP for the United States.   Caution: it is 786 pages in length. Here is the indication in the USA AIP that WGS-84 is the standard used in the USA. It is found in Table TBL GEN 2.1−1

"3. Geodetic Reference Datum
3.1 All published geographic coordinates indicating latitude and longitude are expressed in terms of the World Geodetic System − 1984 (WGS−84) geodetic reference datum."

For those of you flying into Russia and the Commonwealth of Independent States and planning on using your GPS receiver this may prove to be an issue.  Russia uses an different geodetic standard model for its Global Navigation Satellite System (GLONASS) satellite navigation system.  It is the PZ-90 (Earth Parameters 1990 - Parametry Zemli 1990) standard. 
(To be continued...)

Saturday, February 6, 2010

Thoughts On Landing Touchdown Targets and Touchdown Zones

What is the landing touch down target for your landings?  Do you use one? I know most of us are  interested in demonstrating our superior pilot skills by making smooth landings.  In the effort to achieve a smooth landing most pilots will ignore one of the more important goals for landings and that is a touch down on the prescribed touch down target within the touch down zone. A landing on or close to the touch down target will result in a longer length of runway remaining to decelerate and stop enhancing safety.  It will also prevent a landing short of the runway.

I learned to fly in a Piper PA-12 Super Cruiser while  attending Kent State University on a runway that was 3,000 feet long. The flight instructor's name was Leonard Mack.  His preflight briefing for my first effort and landing and takeoff included a rough runway drawing on a black board.  Mack divided the runway into thirds as well as dividing it in half.  He created a touch down target by drawing an X in the middle of the first third emphasizing the importance of having an aiming point for the landing.

He went on to add the criteria of as long as a touch down occurred within the first half of the runway, a deceleration and stop would happen safely. Mack established the rule that says if your aircraft is not able to touch down in the first one half of the runway, a go-around is mandatory. These rules have proven to be of value for more than 40 years for me. They worked no matter what length runway I landed on or what specific aircraft I was flying.

The airlines have established guidelines with similar values.  For example, when I was flying a narrow body airliner like the Boeing 727, the touch down target was specified to be a point 1,000 feet from the approach end of the runway.  If I was flying a wide body airliner like the Boeing 747, the touchdown target was a point 2,000 feet from the approach end of the runway. The primary purpose of these guidelines was to prevent pilots from experiencing an undershoot or touching down short of the runway. As the Boeing 747 was a much longer length aircraft, the touchdown target had to be further down the runway to assure an undershoot would not take place.

The airlines added the requirement that if a touchdown would not result in the touchdown zone a mandatory go around maneuver was required.  The touch down zone was defined as a space that began at a point 500 feet prior to the touchdown target to a point 500 feet beyond the touch down target. Landing beyond the touch down zone was never recommended.

A "good landing" simply requires the pilot to be able to "walk away" from the aircraft.  A "great landing" is defined as one in which the airplane is capable of being flown again.  A "perfect landing" requires both of the above plus a smooth touchdown in the touchdown zone.  Most  pilots I have observed are willing to trade off the requirement for touchdown in the touchdown zone to achieve the smooth landing.   This is not a worth while trade off in my opinion.

In my experience a perfect landing only happens about once in every 100 landings. How often do you experience a perfect landing?

Thanks for taking the time to read my blog.  If you have a blog, please direct me to it and if appropriate we can link them up.

Thursday, February 4, 2010

Unconventional Thoughts on Aircraft Maximum Gross Weight Limitations

Every aircraft has a maximum gross weight limitation established as part of the certification process. I owned a 1974 Cessna Skylane I purchased new for more than 30 years.  It had a maximum gross weight limitation of 2,950 pounds.  Although I made more than one attempt to discover the reason its maximum gross weight was 2,950 pounds by contacting Cessna in Wichita, I was never successful in finding the reason for the establishment of the number - 2,950 pounds...

After doing some research on the issue, I discovered there are different factors which the manufacturer uses to establish the maximum gross weight.  They include structural strength limitations, as well as performance limitations in the form of stall speed criteria.  Another criteria used is minimum climb performance gradients.  Although I was never able to determine which of these were the reason for the 2,950 pound limitation for my Cessna 182, I strongly suspect the reason for the number chosen was the balked landing minimum climb gradient requirement for certification.

In discussions I have had with many, many pilots on this issue of the reason for the choice of the number of 2,950 pounds, none could offer me an answer.  They would mostly guess the structural strength issue as the reason. I did not agree with them in that I felt based upon the 3,000 hours I flew in it, the balked landing go around minimum climb gradient was the reason. This caused me to reach the conclusion that there may be times when it is safer to take off in excess of maximum gross weight if the excess weight is in the form of fuel. (The best substitute for brains is gas and the only time you have too much fuel is when you are on fire.) A little extra fuel offers additional options for each of our flights should we encounter unexpected head winds or bad weather at our destination.

The Federal Aviation Administration will actually approve flights in excess of maximum gross weight by 10% for ferry flights and some normal operations in Alaska. The highest gross weight take off I ever made in my 182 was ???? pounds.
What experiences have you had deliberately flying in excess of maximum gross weight? What are your thoughts on this issue?  Please post them on this blog.

Tuesday, February 2, 2010

What is the technically correct response to this transmission from ATC?

New York Center transmits this message to you: "Falcon 900, contact Cleveland Center one three two point six five". What are the exact words you transmit in response? If you say, "Falcon nine hundred, contact Cleveland Center on one three two point six five" you are not technically correct. Even though today you hear almost all pilots respond with the same 10 words, you are not technically correct. If you refer to chapter 4.2.1 of the Airmans Information Manual which contains the proper radio communication phraseology you will find no requirement to repeat back frequencies. However, there is a requirement to acknowledge the transmission from ATC with your call sign only.

In the days when pilots and Air Traffic Controllers were forced to use low/medium frequency radios which produced lots of static interference, it was common practice to repeat transmissions.  However, today, with the universal use of  Very High Frequency (VHF) radios and the much quieter cockpits of today's aircraft and the use of high tech noise canceling headsets the need to repeat transmissions no longer exists.  It is my opinion every time you repeat the frequency you are contributing to a decrease in safety by creating unnecessary radio frequency congestion. Congested frequencies have become more common with the rapid growth in today's air traffic.

If we all would stop repeating the frequencies a contribution to air safety would be a welcome relief. It may not appear to be a very significant difference on an individual basis but the savings of up to 10 words per frequency change amounts to a large improvement overall.  It results in a less noisy and fatiguing environment  as well as less congestion.

Please help me spread the word to have pilots stop repeating radio frequencies.
What is your opinion? Don't be afraid to post it here as a comment.