Stinson Airport Small Tower Voice Switch

Stinson Field was founded around 1916.  I was told it was the oldest airport in the country.  It was a lot of fun to work there.  Part of the fun was when a B-17 landed just before a large troop of actors arrived to begin using the airport as a backdrop for some TV show.  We had no advanced notification.  Ricardo Montalbon was there.  So were other famous names.  They thought my equipment room was a dressing room, which created a rather embarrassing moment.

I was there to install a Denro STVS.  A voice switch is a system that allows controllers to push buttons to select a frequency for voice transmission, choose to use main or standby radios, to alert the fire station of a problem, to select phone or landline communication paths and to allow recordings of all communications.

I had no training on this system, but it was not too difficult to install.  I was going to finish on schedule, but one day, I came in and noticed something odd.  The sound levels sent from the STVS to the reel-to-reel recording equipment had changed drastically.  At first, I just performed the alignment again and was surprised the next day to find that again, the level had changed quite a bit.  The recording quality was terrible when the sound level was too low or high.  I performed troubleshooting and found that no matter what I did, the problem persisted.  

I contacted the FAA Technical Center and spoke to the engineer who had signed off the system during final evaluation and acceptance.  He was not very helpful.  He said that the alignments procedures were in revision and he faxed me his draft version.  It did not help at all.  I contacted my regional office.  My complaints were considered to be ridiculous.  There were over 50 STVS successfully deployed.  There simply could not be a systemic fault such as I described.  So, I created a written test procedure with a data entry sheet to log the results of various adjustments to the system.  I discovered this way that when the controller adjusted the volume control for the headset, it strongly affected the record level.  There was no reason to design a system to do this, I thought.

The results from this testing were submitted to local, regional and national engineering staff.  My supervisor was getting apoplectic during phone conversations with me, because somebody was building a fire under his chair.  He demanded that I commission it, but I refused.  I told him that it was not certifiable with unreliable record levels.  Controllers were already using it for controlling air traffic, and this was a very illegal situation.  NTSB would frown most severely if there was an investigation.

This forced management to take action.  A team of four engineers arrived without warning.  As I was welcoming them, the first one called me out for "crying wolf" and the second one said something similarly ridiculous.  The last engineer said under his breath, "you deserve an award, but you sure won't get one."

Within a short time, they followed my procedure and verified that my reading were correct and they said nothing and left.  I never heard from them again.  

Then the Sector Manager stepped up to the plate and told me that we needed to do an emergency NCP (NAS Change Proposal).  He suggested that I take the receiver signals and combine them for main and standby radios to create a signal that would have a constant level to provide reliable record levels.  This was a fine idea, and I went ahead and did it.  It did not take care of the landlines, but at least we would be able to hear what the conversation was between the pilots and controllers, in the event of an accident.  I commissioned the system and left.

A few months later, I received an invitation from the FAA Technical Center.  They were performing a review of the STVS because I had flagged it.  My supervisor told me to not attend.  I went anyway.  I sat through that meeting and did not say one word.  There were 5 or 6 people in attendance.  A Denro engineer arrived and I imagined he would have a hard time explaining why it was designed the way it was designed.  Yet, he was as cool and calm as could be.  He made his presentation and made a point of emphasizing that the voice path into the recorders had no AGC (Automatic Gain Control).  I was stunned and somebody else asked why there was no AGC.  Every other voice switch has AGC.  The Denro engineer calmly explained that this was a design requirement provided by the FAA.  We all turned our attention to the executive who was running the meeting as he chomped his unlit cigar.  He simply said, "Air Traffic demanded that we remove the AGC."  That was pretty much the end of the meeting.

It might have been appropriate to explode into expletives, but I remained silent.  I had to think about this.  I talked to some people and learned this was reportedly the case.  The Air Traffic controllers' union, NATCA, apparently wanted AGC removed.  Well, fine and dandy.  NATCA might also want free massage therapy at every facility.  NATCA should not get everything NATCA wants. Engineers have responsibility and one of those was to ensure that the best possible recordings were made, whether the people getting legally recorded want good recordings or not.  But, AT has a lot more prestige than engineering.  Sycophancy is hard to overcome.

To my knowledge, Stinson remained the only facility with the modification I had installed.  The STVS was removed from service around 2009, if memory serves.  My supervisor survived.