It is the chapter 5 problem 41 in the practical management science 6th edition. Please tell me how to apply the restriction about downtime.

41. One rather unrealistic assumption in the flight- scheduling model is that a given plane can fly two con- secutive flights with no downtime. For example, it could fly flight 5903 that gets into Washington, D.C. at time 14 and then fly flight 7555 that leaves Washington, D.C. at time 14. Modify the model so that there must be at least one hour of downtime between consecutive flights. B D E Figure 5.36 Flight Arcs Flight capacity Flight net revenue 25 30 39 24 24 35 29 29 Flight flow 1 1 1 0 1 1 1 1 1 1 1 1 1 1 13 1 35 Flights 36 Flight origin 37 Boston 30 Boston 9.5 39 Boston 12.5 40 Boston 13.5 41 Boston 13.5 42 Boston 16 43 Boston 16.5 4 NY9.5 45 INY12 46 NY13 47 NY14 NY16.5 49 NY1B 50 NY18 51 NY18.5 52 WashDC9 53 WashDC12.5 54 WashDC13 55 WashDCS 56 WashDC14 57 WashDC14 58 WashDC14.5 59 WashDC16 Flight destination NY NY105 WashDC14 WashDCIS NY14,5 WashDC175 NY17.5 Boston 11 Boston135 WashDC145 Boston 16 Boston18 Boston195 Wash20 Boston20 NY11 NY14 NY15 Boston 15 5 NY15.5 Boston 15.5 Boston 16.5 Boston 175 1 1 1 1 1 1 1 1 1 18 22 28 34 39 1 1 1 1 0 1 1 15 12 28 13 1 1 1 18 33 28 19 15 0 0 1 0 1 1 1 B C D Figure 5.37 Ground Arcs Ground flow 1 Ground cost 0 0 0 0 0 0 0 0 0 0 0 0 0 A 61 Ground arcs 62 Ground origin 63 Bastons 64 Boston8.5 65 Boston 66 Boston9.5 67 Boston 10 68 Boston 10.5 69 Boston 11 70 Boston 11.5 71 Boston 12 72 Boston 12.5 73 Boston 13 74 Boston 13.5 75 Boston14 125 WashDC15 126 WashDC15.5 127 WashDC16 128 WashDC16.5 129 WashDC17 130 WashDC17.5 131 WashDC18 132 WashDC18 5 133 WashDC19 134 WashDC19.5 Ground destination Boston8.5 Boston Boston9.5 Boston10 Boston10.5 Boston11 Boston11.5 Boston12 Boston12.5 Boston13 Boston 13.5 Boston14 Boston 14.5 WashDc15.5 WashbC16 WashbC16.5 WashbC17 WashDC17.5 WashDC18 WashDC18.5 WashDC19 WashDC19.5 WashDC20 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 1 1 0 0 1 1 0 41. One rather unrealistic assumption in the flight- scheduling model is that a given plane can fly two con- secutive flights with no downtime. For example, it could fly flight 5903 that gets into Washington, D.C. at time 14 and then fly flight 7555 that leaves Washington, D.C. at time 14. Modify the model so that there must be at least one hour of downtime between consecutive flights. B D E Figure 5.36 Flight Arcs Flight capacity Flight net revenue 25 30 39 24 24 35 29 29 Flight flow 1 1 1 0 1 1 1 1 1 1 1 1 1 1 13 1 35 Flights 36 Flight origin 37 Boston 30 Boston 9.5 39 Boston 12.5 40 Boston 13.5 41 Boston 13.5 42 Boston 16 43 Boston 16.5 4 NY9.5 45 INY12 46 NY13 47 NY14 NY16.5 49 NY1B 50 NY18 51 NY18.5 52 WashDC9 53 WashDC12.5 54 WashDC13 55 WashDCS 56 WashDC14 57 WashDC14 58 WashDC14.5 59 WashDC16 Flight destination NY NY105 WashDC14 WashDCIS NY14,5 WashDC175 NY17.5 Boston 11 Boston135 WashDC145 Boston 16 Boston18 Boston195 Wash20 Boston20 NY11 NY14 NY15 Boston 15 5 NY15.5 Boston 15.5 Boston 16.5 Boston 175 1 1 1 1 1 1 1 1 1 18 22 28 34 39 1 1 1 1 0 1 1 15 12 28 13 1 1 1 18 33 28 19 15 0 0 1 0 1 1 1 B C D Figure 5.37 Ground Arcs Ground flow 1 Ground cost 0 0 0 0 0 0 0 0 0 0 0 0 0 A 61 Ground arcs 62 Ground origin 63 Bastons 64 Boston8.5 65 Boston 66 Boston9.5 67 Boston 10 68 Boston 10.5 69 Boston 11 70 Boston 11.5 71 Boston 12 72 Boston 12.5 73 Boston 13 74 Boston 13.5 75 Boston14 125 WashDC15 126 WashDC15.5 127 WashDC16 128 WashDC16.5 129 WashDC17 130 WashDC17.5 131 WashDC18 132 WashDC18 5 133 WashDC19 134 WashDC19.5 Ground destination Boston8.5 Boston Boston9.5 Boston10 Boston10.5 Boston11 Boston11.5 Boston12 Boston12.5 Boston13 Boston 13.5 Boston14 Boston 14.5 WashDc15.5 WashbC16 WashbC16.5 WashbC17 WashDC17.5 WashDC18 WashDC18.5 WashDC19 WashDC19.5 WashDC20 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 1 1 0 0 1 1 0