A dhc-8 flight crew experienced difficulty with their SELCAL system which prevented them from receiv...

Narrative:

This was a routine flight to ZZZ. While cruising at FL200; we received a SELCAL alert indicating that our dispatch department was attempting to contact us. The captain; as PNF; attempted to reply to the SELCAL; but to no avail. He then attempted to use the system to contact dispatch; while also did not work. This was not surprising to either of us; as the system hardly ever works; and has been a problem for yrs; which is a fact known to both the company and the FAA. As neither the captain nor myself could think of any important reason that dispatch would be trying to contact us; we elected to simply give them a call upon reaching ZZZ to see if they wanted us for anything; or if the SELCAL alert we received was simply a glitch (which also sometimes occurs). The flight continued uneventfully for about another 15 mins; at which point the center controller whose frequency we were monitoring contacted us. We responded; and the controller said that he had been trying to get in touch with us for 60 mi. This came as quite a surprise to us; since we had been able to hear the controller talking to other airplanes on a regular basis during this entire period; and had never once heard him attempt to contact us. We indicated to the controller that we had been on the frequency and had not heard him calling; if in fact he had been trying to reach us. At that point he handed us off to the next sector; and nothing else was said. After landing; we called dispatch and learned that ATC contacted our company dispatch after being unable to reach us on the radio; and that is the reason we received the SELCAL alert. We never determined why ATC was not able to reach us on the radio. It is my opinion that they were trying to contact us on a different frequency for some reason. I do not believe that we missed a handoff at any time; or missed any radio calls intended for us. Luckily; no airspace conflicts or loss of separation occurred as a result of this incident. However; it highlights once again the unsafe situation created by the defective SELCAL system in our airplanes. If this had been a critical situation; our dispatcher would have had no way to communicate with us at all.

Original NASA ASRS Text

Title: A DHC-8 FLT CREW EXPERIENCED DIFFICULTY WITH THEIR SELCAL SYSTEM WHICH PREVENTED THEM FROM RECEIVING A MESSAGE FROM DISPATCH REGARDING A MISSED FREQUENCY CHANGE.

Narrative: THIS WAS A ROUTINE FLT TO ZZZ. WHILE CRUISING AT FL200; WE RECEIVED A SELCAL ALERT INDICATING THAT OUR DISPATCH DEPT WAS ATTEMPTING TO CONTACT US. THE CAPT; AS PNF; ATTEMPTED TO REPLY TO THE SELCAL; BUT TO NO AVAIL. HE THEN ATTEMPTED TO USE THE SYS TO CONTACT DISPATCH; WHILE ALSO DID NOT WORK. THIS WAS NOT SURPRISING TO EITHER OF US; AS THE SYS HARDLY EVER WORKS; AND HAS BEEN A PROB FOR YRS; WHICH IS A FACT KNOWN TO BOTH THE COMPANY AND THE FAA. AS NEITHER THE CAPT NOR MYSELF COULD THINK OF ANY IMPORTANT REASON THAT DISPATCH WOULD BE TRYING TO CONTACT US; WE ELECTED TO SIMPLY GIVE THEM A CALL UPON REACHING ZZZ TO SEE IF THEY WANTED US FOR ANYTHING; OR IF THE SELCAL ALERT WE RECEIVED WAS SIMPLY A GLITCH (WHICH ALSO SOMETIMES OCCURS). THE FLT CONTINUED UNEVENTFULLY FOR ABOUT ANOTHER 15 MINS; AT WHICH POINT THE CTR CTLR WHOSE FREQ WE WERE MONITORING CONTACTED US. WE RESPONDED; AND THE CTLR SAID THAT HE HAD BEEN TRYING TO GET IN TOUCH WITH US FOR 60 MI. THIS CAME AS QUITE A SURPRISE TO US; SINCE WE HAD BEEN ABLE TO HEAR THE CTLR TALKING TO OTHER AIRPLANES ON A REGULAR BASIS DURING THIS ENTIRE PERIOD; AND HAD NEVER ONCE HEARD HIM ATTEMPT TO CONTACT US. WE INDICATED TO THE CTLR THAT WE HAD BEEN ON THE FREQ AND HAD NOT HEARD HIM CALLING; IF IN FACT HE HAD BEEN TRYING TO REACH US. AT THAT POINT HE HANDED US OFF TO THE NEXT SECTOR; AND NOTHING ELSE WAS SAID. AFTER LNDG; WE CALLED DISPATCH AND LEARNED THAT ATC CONTACTED OUR COMPANY DISPATCH AFTER BEING UNABLE TO REACH US ON THE RADIO; AND THAT IS THE REASON WE RECEIVED THE SELCAL ALERT. WE NEVER DETERMINED WHY ATC WAS NOT ABLE TO REACH US ON THE RADIO. IT IS MY OPINION THAT THEY WERE TRYING TO CONTACT US ON A DIFFERENT FREQ FOR SOME REASON. I DO NOT BELIEVE THAT WE MISSED A HDOF AT ANY TIME; OR MISSED ANY RADIO CALLS INTENDED FOR US. LUCKILY; NO AIRSPACE CONFLICTS OR LOSS OF SEPARATION OCCURRED AS A RESULT OF THIS INCIDENT. HOWEVER; IT HIGHLIGHTS ONCE AGAIN THE UNSAFE SITUATION CREATED BY THE DEFECTIVE SELCAL SYS IN OUR AIRPLANES. IF THIS HAD BEEN A CRITICAL SITUATION; OUR DISPATCHER WOULD HAVE HAD NO WAY TO COMMUNICATE WITH US AT ALL.

Data retrieved from NASA's ASRS site as of May 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Attributes
ACN	809789
Time
Date	200810
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	msl single value : 20000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zzz.artcc
Operator	common carrier : air carrier
Make Model Name	Dash 8 Series Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	cruise : level ground : maintenance
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : cfi pilot : commercial pilot : instrument
Experience	flight time last 90 days : 200 flight time total : 3500 flight time type : 2700
ASRS Report	809789
Events
Anomaly	aircraft equipment problem : less severe
Independent Detector	other flight crewa
Resolutory Action	none taken : unable
Supplementary
Problem Areas	Aircraft Company Flight Crew Human Performance
Primary Problem	Ambiguous

A dhc-8 flight crew experienced difficulty with their SELCAL system which prevented them from receiving a message from dispatch regarding a missed frequency change.