AboutDottie Norkus Expertise I can address questions concerning: airline pilot employment & entry level airline careers in the Unites States, women pilots, flight training, pilot certification, flight scholarships (mostly for women), aviation & airline safety topics, aviation accident investigation, air carrier accidents and airline operations.
***Please note, I cannot address flight training or career queries from outside the United States. If you are not in the USA, please direct your question to the message boards at www.PPRUNE.org as you can surely find an answer there. For those in India try http://www.indianpilots.com
Also, I cannot address questions about aero engineering degree programs/careers or aviation management careers.
Experience U.S. Regional Airline Pilot. I have also had 15 years previous experience in airline ground operations, as well as a part 91 commercial skydive pilot and ferry pilot.
Organizations I belong to I am a charter member of Women In Aviation International as well as the International Organization of Women Pilots: the Ninety Nines. I keep a database of flight scholarships for women (mostly SW USA) and mentor student pilots.
Education/Credentials Embry Riddle Aeronautical University certificate in Aviation Safety/Accident investigation.
Question Why can't planes take off and land in heavy fog?
Answer Damon
They can, with certain criteria met. With certain minimum visual referances, planes can take off in fog. Landing is another matter. Of course, certain criteria must also be met for landing as well.
There are several different levels of bad weather approach catagories. Depending on how an aircraft is equipped, they can only execute the highest level for which they are equipped.
CATEGORY I/II/III approaches refer to different levels of low visibility ILS approaches. CAT I is the least severe at 1/2 mile or 1800 RVR/runway visual range (a measuremt of runway visibility via transmissomitters near the runway.) CATIIIc is a zero/zero ILS requiring and autoland capable aircraft.
There are some jets that can do totally automated landings in very dense fog, but they are the exception more than the norm. To execute a totally automated touchdown in zero forward visibility not only must the airports approach be a Catagory 3/"CATIIIc" certified "ILS/Instrument Landing System", the aircraft must be equipped to use it (CATIIIc certified aircraft/autopilot) and the crew must also be trained and have a recency of experience to do the approach.
Due to the time and expense needed versus the actual times this can be used many airlines chose not to install it.
Airplanes with CATIIIc capability have at least two, and usually three autopilots that operate together during an autoland so if one fails there is a backup to get the airplane down. Each of the autopilots has its own dedicated inputs (i.e. power sources, control positions sensors, attitude and directional data, etc) to reduce the possibility of a single failure in the system that would result in bad things. If any one factor is missing it cannot be done. Additionally, most aircraft are not CATIIIc certified for zero/zero landings. Many are CAT II or even CATI certified, so in foggy conditions below their landing criteria, they will not be able to even initiate an approach to the airfield per Federal Aviation Regulations. In instances where this is the case, that is why the airport is "closed" to those flights, even if the airport does have a CATIIIc ILS.
