Edit in JSFiddle

angular.module('sample', ['firebase'])
.controller('sampleController', function($scope, $firebaseObject){
    var ref = new Firebase("https://publicdata-airports.firebaseio.com");
    $scope.sfoAirport = $firebaseObject(ref.child('SFO'));
});

<div ng-app="sample">
    <div ng-controller="sampleController">
        <div>{{sfoAirport.city}}</div>
        <div>{{sfoAirport.state}}</div>
        
        <div ng-show="sfoAirport.delay">
            There is a minimum delay {{sfoAirport.status.minDelay}} of and a maximum of {{sfoAirport.status.maxDelay}} reported.
        </div>
        
         <div ng-show="!sfoAirport.delay">
            No Airport delays reported at SFO.
        </div>
    </div>
</div>