Date: 201212
Local time of day: 0001-0600
Location: MKE.Airport, WI
Aircraft: Regional Jet 200 ER/LR (CRJ200)
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Flight phase: Final Approach
Airspace: Class C MKE
ATC / advisory: Tower MKE
Reporter organization: Government
Reporter function: Local
Reporter qualification: Air Traffic Control Fully Certified
Anomaly: ATC Issue All Types
Detector: Person Air Traffic Control
Result: General None Reported / Taken
Contributing factors: ATC Equipment / Nav Facility / Buildings; Procedure
Primary problem: Procedure

Narrative: The airport authority discovered a hole in Runway 25L in the safety clear zone of Runway 1L. They closed Runway 1L and Runway 25L for emergency safety repairs. Runway 31 is normally restricted to prop aircraft use only. The airport authority lifted the restriction on jets. Due to lower ceilings I advertised the RNAV Runway 31 approach. At one point there was a CRJ inbound from the northeast. The data tag had a VV in the block to indicate they were on a visual approach. I was not in communication with the aircraft; but based on their proximity to the airport I should have been. I contacted Approach to inform them I was not talking to the aircraft yet. During the call we discussed the aircraft being at an altitude below the MVA. The Controller said the MVA was 2;100 on Map 39. I explained that Video Map 39 was for use when we are on MKE RADAR. As they were on MULTI RADAR VIDEO Map 43 depicted the MVA and it was 2;700 where the aircraft was located. I am not certain if the aircraft was cleared for a visual approach prior to entering the higher MVA around the MKE airport. Most controllers seldom work the MKE Sectors combined with the Ripon Sectors. It mostly occurs during reduced staffing on third shift; so they have less familiarity. Months ago; when I was briefed on the new video maps for the MVA; while it was not pointed out; I noticed a change to the higher MVA at the MKE Airport area. I asked about a change to VIDEO Map 43 which raised the MVA in the MKE airport area to 2;700. I stated it would change the altitude usable to the east when clearing aircraft for approaches while on MULTI RADAR. As it also raised the MVA to the south of the airport; I asked if it would raise the altitude I could use to clear aircraft for the ILS 1L or other 1L approaches. The person giving the briefing made a comment that they did not know the answer and no one had noticed or commented on the change in altitudes for clearing aircraft for approaches from the east or south. I pointed out that the higher MVA would affect vectors for visual approaches and could become an issue with icing and aircraft requests for lower in the coming months. I asked what structure built that caused the change to a higher MVA but they did not know. I asked for clarification but months went by without receiving any. About two weeks ago I again asked about the issue with the MVA and what altitude aircraft should maintain until established due to the change. They agreed that 2;700 would be the appropriate altitude to use for instrument approaches from the east and said they would check on the 1L instrument approaches from the south. About a week ago they told me I was probably right and should use the higher 2;700 MVA when clearing aircraft on Runway 1L instrument approaches. They said it was probably safe to use a lower altitude because the MVA should not have been raised to 2;700 in that area as it was not needed that high. I am uncertain what the MVA will be when the new maps come out. Once the answers to the questions about the higher MVA clearly determined that there was an impact due to the change; controllers needed to know. At the very least there should have been a mandatory pre-duty briefing item to inform controllers of the impact of the higher MVA around the MKE airport while working Multi RADAR as it was a significant change in the MKE airport area. Additionally during this time the aural alert for CA (Conflict Alert) and LA (Low altitude Alert) was out of service at my Local Control position as maintenance had accidental disabled it during a previous shift. This got me thinking about the higher MVA. With the aircraft low and outside the normal parameters of the Runway 25L final as they made the approach to Runway 31 the alarm for low altitude never went off at any of the other positions in the Tower. Was the higher MVA for safety given to the STARS system programmers for when controllers are on MULTI RADAR working all sectors combined? As the MVAs are different around the airspace based on whether I am using single site RADAR in an area or MULTI site RADAR presentations why is there no entry to the STARS to tell it to use a different terrain collision audio and visual alert. If it is not safe for me to vector at those lower altitudes shouldn't the STARs be programmed with two sets of terrain collision alert sets based on whether single site or MULTI RADAR is being used in a sector?




Synopsis: A MKE Controller voiced concern regarding the MVA requirements in the local area when various RADAR sites are being used. He recomends more detailed briefings for the controllers regarding the applicable requirements.