Airways said the earlier delay was in fact caused by an air controller's car breaking down.
Robinson said regional control towers were operated by a very few men and women. This included Napier which had only two shifts – one in the morning, and one in the afternoon.
"Staffing the network with the smallest number of controllers to save on costs makes regional aviation services vulnerable and creates a single point of failure.
"In the case of yesterday, this puts considerable pressure on those staff to cover each other's shifts, sometimes at very short notice if there is a family problem or illness, for example,'' said Robinson.
Airways — which runs the air traffic system— is investigating using remote' digital towers control traffic in some regional centres.
Controllers at central locations would be able to monitor the airfield by video and tracking systems. The state-owned enterprise has already said the new tower in Wellington in among the last of the big traditional towers it would build.
There are about 350 controllers throughout the country with most in Airways' Christchurch and Auckland bases.
Robinson is an airline pilot and said his group would always support the benefits of improved technology but even the best and most complex digital system would never replace the highly skilled and experienced air traffic controller.
"A centralised remote tower system would potentially exacerbate the skeleton staff situation as that means a further reduction to one person per shift to operate and control the airspace over a multiple number of regional airports.''
In its recent submission to the Government's Employment Relations Amendment Bill, the association has told a select committee that given the profession was widely recognised as one of the most stressful occupations in the world.
It had the highest need for mental alertness, and also restricting the ability for air traffic controllers from having 'normal' breaks like other workers was ''irresponsible and unsafe,'' and could potentially lead to a serious incident or accident.
"At regional airports they are often solo controllers working the shift by themselves. This means that they have the sole duty to ensure that the aerodrome and surrounding airspace remains safe.''
Robinson said his association would write to Nash outlining this situation and asking for his support to address minimum staffing issues.
''This will assist so he is no longer 20 minutes late on his flight to Wellington, and that both passenger and employee safety is not compromised," Robinson said.
Comment has been sought from Nash.
Airways this afternoon said staffing levels were set to accommodate an anticipated level of staff illnesses, leave and other expected absences.
It said it consistently operated at 99.8 per cent service availability around the country.
The level of service it provided at each of our 21 service locations nationally was determined by law and agreed with airlines and airports to balance safety, their operational and scheduling requirements and the costs of delivering the service, said an Airways spokesperson.
Napier handles about 24,000 flight movements a year. It had a staff of five controllers who worked solo watch shifts.
''Usually this is sufficient to cover all eventualities, but there is always the possibility that a number of expected and unexpected staff absences may occur at once, and these are difficult to cover at short notice.''
Airways also reiterated its response to ALPA's submission to the seliect committee, saying it was satisfied solo watch was safe.
'Due to low traffic levels at some aerodromes, air traffic control services are provided by one air traffic controller at a time (solo watch) with two shifts per day,'' it said.
During each shift at these towers there were typically several sustained periods of more than 30 minutes with no traffic movements where controllers could have a meal and take a toilet break.
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