Alan,
Thanks for your respnses.
1. When the countdown timer is activated, only the flight mode type and timer are displayed during flight, i.e. your screen was displaying correctly - refer display picture in manual. Display reverts to normal when TX turned off and on again as you experienced.
A1 - You are correct. I was not aware of that and thought it indicated a problem. Admittedly, I don't look at the screen much while flying.
2. There are two very different Flash 5, the first of which requires that you cut and save any changes, the second Flash 5SX has auto save. Problems could occur if adjustments had been made before flight and not saved properly or even if TX has been allowed to overheat sitting out in the sun or in a closed up vehicle exposed to hot sun.
A2 - Mine requires the Cut/Save prior to power down. This was done. Unit was in the shade between flights and Saturdy was a cooler day than previous weeks.
3. How old are the batteries, keeping a good charge and RX upto peak current demands? black wire corrosion could be setting into the leads and connectors leading to intermittant and/or zero operation. Note that if TX powered off and on during that flight, you would have lost the flight countdown timer setting and reverted to normal screen.
A3 - Batteries are new - recently upgraded to a 2000 mAh NiMh pack and it was fully charged. Count down timer was still functioning after incident.
4. Suggest range test for an extended period. If for no other reason than peace of mind, being due for a tune up anyway, send in for service as below.
A4 - Happened during second flight about 8 minutes into it. My range had been very far in relation to where the plane was when the incident happened.
I am considering check up time. However, having been an Electronic Technician early in my career, I know the difficulty in finding an intermittent problem.

Again, thanks for sharing your knowledge and experience.
KW_Counter