Mode C/S

[tomtom_91]

I am a little confused about this... (n00b) Why would a pilot not sqalk mode C it there seems to be lots of adverts at the moment (Air Space Safety: Downloads).

Just confued about why this is? Do pilot forget??

Sorry about the silly question

Thanks

Tom

[cottam approach]

If he'd inadvertantly flown into controlled airspace and didn't want anyone to know about it!
Or if is was u/s, out of tolerance

[simfly]

Like a GR4 who went over the wash the last 2 days, with broken transponder.... lots of avoiding action to helis operating offshore until the mil owned up to controlling it - was above FL200!!! but we weren;t to know...

[Radarspod]

If your transponder and altitude source are serviceable, then at all times you should provide Mode C information (pressure altitude for Mode S installation). It is much more beneficial to controllers to know where you are in 3 dimensions as vertical separation is incredibly valuable. Mode C information also aids TCAS tracking algorithms so further improves safety.

However, it is probably as dangerous, if not more, to provide false Mode C information as it may cause confusion or false sense of separation. In this instance, if the false information is identified, ATC may ask the pilot to stop providing this information (not an ATCO - sure someone will correct if wrong), normally by selecting the transponder selection before 'ALT' (ON?) to deactivate responses to Mode C or Mode S UF4 interrogations.

RS