The provincial government just issued an order that could throw a wrench into several plans for high-rise developments in Toronto — and it all has to do with airspace for helicopters.

Ontario's Minister of Municipal Affairs and Housing, Paul Calandra, issued a Ministerial Zoning Order (MZO) in late January that lowers the heights of protected flight paths for air ambulances serving St. Michael's Hospital and the Hospital for Sick Children.

The MZO — which has no avenues for appeal — went into force on January 26, and effectively slashes the maximum heights for developments within a series of cone-shaped areas extending from the two hospitals.

These areas include three cones extending east, west, and north from St. Mikes, and two cones extending east and west from SickKids.

The areas around the two hospitals that will have new maximum height developments.

As with previous flight path restrictions, these cones taper down in height limit towards their sources at these two hospitals, with height caps gradually increasing/decreasing at intervals that allow helicopters to safely ascend and descend without sacrificing too much forward momentum.

Only developments where building permits have already been issued are exempt from this MZO, which is set to expire on May 30, 2025.

This means that proposals which have sunk extensive costs into design, planning, and approvals processes — even those have been greenlit by City planners — are suddenly being forced back to the drawing board to conform to height limitations.

Other exceptions may be considered for temporary incursions into the flight paths, like construction cranes and related equipment, though no permanent structures will be permitted within these flight paths through the duration of the MZO's implementation.

The change will impact all forthcoming developments in the highlighted regions that don't already have building permits.

One of the many projects subject to these height restrictions is the CreateTO effort to select a proponent for the proposed redevelopment of Toronto's Coach Terminal. Other projects further along in their planning stand to lose much more money through redesigns.

According to business law practice Cassels, the City of Toronto is expected to update its zoning by-laws regarding helicopter flight paths, which established the pre-January 26 height restrictions.

Provincial MZOs have been the source of much controversy under Doug Ford's leadership, and several instances of these orders benefitting developers have spurred scrutiny over relationships between Queen's Park and the homebuilding industry.

However, this is one MZO that developers and the masses in urgent need of housing are less likely to welcome with open arms.