"Downtown is pretty precious and we don't want to lose capacity to prevent a major fire there.
"I'm sure they (FENZ) understand that and will be working to resolve it."
McDouall said he had a briefing from FENZ representatives last week.
"I was assured that none of the capacity would be lost. That gave me a hell of a lot of comfort."
While there was more to the dispute than just pay, he was "absolutely sure" firefighters weren't paid enough.
FENZ also attend purple [immediately life-threatening] calls, with cardiac and respiratory arrest.
"Since there has been a formal expansion of their role, which is what they were doing anyway, they are Johnnys-on-the-spot," McDouall said.
"I know firefighters personally and they are great people who are committed to the community and their work, however hard it is."
Whanganui members of the New Zealand Professional Firefighters' Union joined the national strike action last month.
It addresses pay, working conditions and understaffing.
A joint statement between the union and FENZ on Monday said both parties were working on a process to re-engage constructively in collective bargaining.
A mutually agreed third party would be engaged to support and assist this re-engagement.
FENZ Te Ūpoko (Napier, New Plymouth, Whanganui, Palmerston North, Wellington) region manager Bruce Stubbs said there was an electrical fault on the Whanganui aerial appliance.
"This is causing the aerial component to operate slower than normal. The appliance is currently in the workshop to get this fixed."
It was rare for an aerial to aid the escape of people from a burning building, Stubbs said.
"In the initial stages, aerial fire appliances aren't usually used for firefighting in high-rise buildings where people live because firefighters use the fire safety measures and equipment inside the building – for example sprinkler systems, internal firefighting water systems (risers), protected access and egress pathways."
Aerial fire appliances were primarily used to deliver water from height onto a fire, as an observation platform, to prevent fire spread to neighbouring buildings, or to provide lighting, Stubbs said.
"If aerial fire appliances are sent to an incident they are not used until we know that any people still inside the building are out of the way of the water jets."
On Monday the union said there were now no available heavy aerial appliances between Hamilton and Dunedin, with the Christchurch appliance going offline for servicing.
Firefighters would instead crew a converted concrete-mixer.
